the real reason (besides laziness and daz stock models) is that people who haven't studied classical art rarely have any clue how to make 'realistic' look beautiful. it's Hard and takes years if not decades of drawing and painting, and the required skill level is rare even among artists. essentially the problem is that if you can't draw it beautiful, it means you don't know where the lines should go to. and if you don't know that, it doesn't matter if your 'brush' is a real brush, daz sliders or a camera.
so the two main variations to adress this that we see here are:
1) giving up, and using stock models. which look boring but forgettably beautiful. and
2) trying to stretch the extremely restricted envelope by making your own characters. admirable, but often the result is hideous because that's just the level your artistic technique is. you simply won't see the problem because your brain was never conditioned to see it. it's not something you can just will or hope into existence any more than you can pick up an instrument and play it masterfully. it's not realistic to expect that you could, in fact it's insanely delusional. you need to take years off training classical drawing every day before you can do it.
so when I see people try pushing the envelope, I always love it. I can see what they're trying to do. but it's also painful to see the ignorance in the comments when people don't understand how Good the models in light of my life look.
what can we do about it? obviously not a lot. hire seasoned artists if it's your own game. but as that's not gonna happen we'll just have to try looking past it in both cases. we'll just have to live with the landlady looking like a 23yo model after airbrushing, or the kinda grotesque attempts at making her look 45 but ending up with 23yo body with a 70yo skin.
and in the rare, so rare occasion that we see someone trying and not failing, appreciate that rare gem. you'll see less than 1 out of 100 games like that. so even if it's not your thing, its not like your porn life is ruined. you'll almost never see it again.