Sorry, thought you were saying it was.
No, don't think so. Would it add to the tragedy? Yes, of course. However, PTSD, losing friends, feeling like you sacrificed everything for a king who didn't deserve it, yeah, that could lead anyone into a life of depression and just living for the next drink.
It's character work, fine enough. As far as why Hawkeye has a nuclear family, that is how it is in the source material, just like it is for Valkyrie being LGBT.
Don't remember the Black Widow bit (although she did flirt a lot with Cap, even if it wasn't serious on her end). Now that you mention it, I do recall Falcon wondering if Cap would visit him at his job, since it would impress the women there. Thought it was simple way to set up Cap visiting him later in the movie and injected a little humor. Wouldn't've changed any had it been a gay character in the scenario, IMHO.
Don't see the difference between the two in regards to character world, "relevance," etc., and I'd always argue that "organic" writing serves anything better then not (e.g. pick one and write it well, not "using the claim of "bad writing" to argue against something you didn't want). Heck, did Life is Strange need a possible boyfriend character when all the narrative drive was in the relationship between the female lead and her female best friend/love interest (depending on the player's choices)?
Uh, the franchise has done that quite a bit across the board?