Part of why Leon works characterization-wise in RE4 is that he's fundamentally true to his RE2 incarnation in how people react to him. He was originally defined by no one listening or taking him seriously, ever, so there was a nice turnaround on the default entitlement usually afforded to leading men in fiction. 4 amps up his performance as a supposedly confident and suave proactive agent to support the fantasy of inhabiting that skillset in the game's over-the-top farce, but that core appeal is still present as for all his carefully practiced affectations he's still ridiculed by nearly everyone he meets, or shot down immediately for his Solid Snake come-ons. He is an empowered character but one who regularly takes pratfalls to land him on the better side of endearing as a result, possessing ample privilege to weather those blows. I'm not a very big fan of RE4 but RE8's simultaneous courting of its overall iconography and concepts and the tonal dissonance that resulted in made me take stock of what actually worked there both narratively and otherwise, in contrast. Whatever the older game is, I think it's a work of far clearer tonal confidence and clarity.
Ethan, in addition to everything discussed for how he's positioned in the story, is also on a personal level just kind of unpleasant which marks most of the modern writing associated with the series for me. I used to be drawn to RE because it was a horror cartoon, gruesome and gory, but at the same time tame and chaste. No one fucks, no one trades insults or uses profanity beyond a PG rating if even that. Over time, "maturity" has crept in in people throwing around their fucks and bitches and other really mean-spirited, barbed putdowns. Ethan's one-liners aren't even good but they still feel like they have to punctuate every boss encounter's conclusion with them, and it especially rankles with characters like Moreau who are so obviously victims of something larger than themselves and they're not afforded anything but base insults for their appearance and circumstances from the player avatar. They're not supposed to make me resent Ethan or have his actions serve as a criticism of him as all the concerns of the storytelling are in strict idolatry of his motivations and drive to go on, yet I've never felt as hollow inhabiting any other character in the series as a result of the writing itself.
Doesn't he actually say something that almost approaches sympathy about Moreau after that fight? I don't remember and it didn't land, but I feel like they made the most perfunctory effort possible. I thought Ethan was fine in RE7 as a kind of everyman cypher. Like, yeah, usually it's cops, or special cops, or soldiers, or whatever who deal with this stuff, but how about this REGULAR-ASS DUDE? He's fighting mold monsters! He's confused by hidden doorways and keys with dumb shit stapled to them! But in 8 there's a moment early on, when you're at the house with all the survivors where he practically quotes Die Hard 2: Die Harder saying something about "how can the same thing happen to the same guy twice?!" And at that point I just... kinda stop being invested in him as a character?
As for Leon, he feels like a slightly less-dorky Ash Williams in RE4. In fact, Leon kinda makes the jump from Evil Dead Ash to Army of Darkness Ash from 2 to 4, without a stopover at Evil Dead 2 Ash (which is a shame, really). But they've honestly gone and fucked him up, too. I didn't like 6 for a multitude of reasons, most of which related to the terrible Design-by-Committee feel (which RE8 honestly also has, to an extent, but at least the HUD doesn't change from section to section), but boy, did I ever hate "Serious Action Hero Leon S. Kennedy" a whole lot. And if he's like that (similar to how he looks in that new Netflix show or movie or whatever it is) in this rumored RE4make, boy, that will sap a lot of the fun out of it. (I hope they have enough sense to not do that. They kept him a naive little baby in RE2K19, so hopefully they stick to what worked in a potential RE4make.)