This is a question I have been asked before, and it's not one I have ever been surprised, offended, or annoyed at receiving. As far as Metal Gear villains go, and hell, even as far as villains in general go, he really isn't particularly likeable.
But like I said on the last page, my taste is terrible so here we are. Spending what is at the time of writing almost a year and two months of my life fixating on a weird looking, horrible skull man. So let me at least try to explain.
I have always liked villains. I'm not sure who the first was, maybe Scar from The Lion King or something along those lines, maybe even villains as harmless as Team Rocket for all I know. This love for fictional assholes has basically never stopped evolving throughout my life, and here I am now, a grown adult, a proud villainfucker.
Villains are obviously sexier, I mean, that goes without saying. Just look at him. Dressed in all black, tall boots, leather gloves, fancy coat and waistcoat - even the silly domino mask and hat are sexy as hell with the way he wears them. And the inhumanity of him, that's even sexier! Monsters, aliens, robots, they all get a big "yes" from me. I do genuinely find him beautiful, his scars and pale skin are so striking, such a fascinating character design. I always gravitate towards kind of weird looking guys in fiction (again: the monsterfucker thing) and he's definitely one of the weirdest! I know, categorically, he is incredibly ugly and designed to look that way, but to my weird brain I just go "ah, yes, this is the prettiest fictional man ever designed".
There's also the voice - so deep and evil! People give him shit for sounding so over the top and dramatic, but I love that about him. As someone who is at heart very dramatic and over the top when I want to be, I just get it! And besides, James Horan did a wonderful job chewing the scenery as him, what more could you ever ask for in a fictional character than that? Where's the fun in him talking and acting like a real person, anyway.
Villainfucker rambling aside, though, there's a deeper meaning to the villain thing to me. Villains are always the people I've seen myself in. Heroes are hard to relate to, because I don't really see myself as one. I don't mean that in a "I kill people" way, and in absolutely no way do I approve of or believe Skull Face's long list of crimes are okay or worth replicating, but there's something about villains in fiction - in good fiction, at least - that I find to be a really raw representation of humanity, and the worst parts of that.
Villains in media usually end up as villains because of something they've endured. Some kind of painful event, a prolonged feeling of suffering or injustice. Skull Face kind of defines that - spending his youth suffering, childhood years wasted on the pain of losing his identity over and over again. He didn't do anything to deserve it, didn't have any say in the matter. It just happened and he was powerless to do anything about it. I've never been burned alive, had my language taken from me, or my body filled with parasites, but in a weird way... I get it. Having things happen to you that you can't control and can't understand, living with the grief and bitterness of having to go around bearing the lifelong consequences of something fully beyond your control. Expected to just keep on living with the knowledge that your life was made more difficult before it ever really started. To take responsibility for something that wasn't your fault. To keep on living and behaving as you did before when everything about you has been taken apart and altered forever.
I know our pain isn't comparable, but... I don't think fiction and real life are ever meant to be directly comparable. Fiction is there to depict the unreal - even the most down to earth fiction is still nothing more than a fantasy, a product of someone else's brain. But that fantasy is always influenced by real experiences, things the creator went through, things they read about, heard about, saw happen to others. Fiction is the depiction of real life through the lens of fantasy. So there's always a bit of real life humanity in there, at its core.
You don't need to be a clone to understand the humanity behind Metal Gear Solid 4's reunion between a terrible father and the son who inherited his sins. You don't need to be a soldier to understand what it feels like to be Naked Snake, forced to do an awful act for the greater good, you don't have to be manipulated by world-controlling AIs to understand what it means to be Raiden and have your identity dictated to you by others. No matter how fantastical the context, how unreal the characters, the setting, the experiences, fiction is made by humans to reflect humanity back at us.
I haven't gone through anything that Skull Face has gone through. But I see the humanity in his reaction to it. And to me, it's some of the purest, rawest humanity - the urge to let your suffering make you a terrible person. That urge to go "well, I didn't cause this, so I sure as hell aren't fixing it". The urge to wallow in it. The urge to make it worse.
It isn't something I actively try or want to do. It's definitely not something I encourage. But there's something so human about it, about becoming a villain, and dragging the whole world down with you. To let your pain define you to the very end, never getting over the horrible thing that happened to you for the rest of your miserable life, and making it everybody else's problem. It's like the basest urge as a human - to just become a rotten person and refuse to get better. To become the thing you hate.
So it's something of a kinship, I guess. He isn't the first villain I've felt this way with, and I'm sure he won't be the last. It's a form of comfort, I suppose, finding a character that's like a vessel for negativity, a place to store it all and express it through, without having to become the actual shitty person yourself. I'm sure it's in no way maladaptive.
There are other things, too, not just the miserable edgy part of my brain. We are both united in our love of language, especially in terms of sociolinguistics and the sociology of language. When The Phantom Pain came out, long before I ever got into the Metal Gear series, I was just starting a university course on my country's native language and culture, well, before it was forcibly endangered through the dominance of English. So believe me, I fully understand where he's coming from. The way he goes about it is obviously both very stupid and very evil, but his core idea (English sucks and is ruining everything) is completely accurate.
We're also both complete and utter windbags. That jeep speech was nothing compared to the kind of rants I can go on. I wish we could hang out and just talk about minority languages and cultural oppression for days at a time. And watch some spaghetti westerns too, I can tell he's a big fan of Lee Van Cleef. A For A Few Dollars More watchparty would be nice.
The final thing is: I don't feel like a human either. I never have, or at least, not since the aforementioned Events that permanently broke my brain apparently. I'm just some weird foreign creature here, which is part of why I've always been so drawn to robots/aliens/non-human creatures (outside of them being hot). It's hard for me to identify with people, and I'll always feel like an outsider that doesn't belong no matter where I go. So when I see a fucked up monster man with basically no humanity left at all, I'm like, wow, big mood. So if me and him ever get to hang out and he doesn't, I don't know, infect me with a bunch of parasites, I hope we can bond over that thing too.
It's funny that in canon he's this nobody character that spends so much time in the shadows he's basically completely forgotten when he dies, and then even in the fandom he's completely ignored almost all the time or only mentioned when someone is talking about how terrible his character is. Maybe being isolated weirdos with no social circle and a history of being forgotten is something else we can bond over.
I don't want this to get into self-pity territory, although it's probably several paragraphs too late for that. But I'm glad Skull Face exists. Even though nobody else seems to really care about him as a character, he means the world to me. He's an outlet, a source of comfort, a sexy skull man, another weirdo husband for my shockingly long list of weirdo husbands. What more could I ask for. I hope he lives inside my mind forever.