and we don't need every character to look like what is perceived as being beautiful.
The problem is, at heart we're still talking about what is essentially porn. Unattractive characters might be more
realistic, but players won't necessarily want to hook up with/have sex scenes with those sorts of characters. Sure,
some players will (for one reason or another), but many wouldn't. A game full of unattractive characters is more likely to drive potential players away, cost the dev money, and so on.
It's sort of the same reason why Hollywood doesn't cast genuinely unattractive or nerdy people to play ugly characters and nerds. Because at the end of the day you're still making a product you want people to find aesthetically pleasing. So it's better to just put a really hot chick in a frumpy sweater, give her glasses, and put her hair in a ponytail and pretend that she's hideous than it is to actually find an ugly actress.
Yeah, I don't know what happened to the term MILF that it transformed to mean "any" woman who is a mom (I've seen it used for 18 year old women with newborn babies).
Porn happened, probably.
All too often you have porn actresses in the mid-to-late 20s who do up their hair in a more conservative way, put on make-up to look a little older, and suddenly you have "MILF porn", even if those same actresses will then turn around, redo their hair into pigtails, do their make-up slightly differently, and pretend to be teens.
So people who watch lots of porn are going to sort of start to associate the idea of MILF porn with those younger women. You're not going to get a ton of 40+ porn (even though that type of porn certainly exists) as the mainstream assumption of what MILF porn is.
The limitations of computer graphics probably don't help things (HS games probably make old age nearly impossible to model well, and Daz just tends to make characters look uglier more than it makes them look attractively old). But the devs' perceptions of what an attractive "mommy" character is supposed to look like probably plays a bigger role. And they're going to base it more on Hollywood and porn than they are the sorts of women you meet around that age in the real world.
It's sort of similar to how most games on this site that have characters in college always seem to treat college more like high school. It's not really accurate at all, but it's how people tend to perceive things based on how Hollywood (and porn) presents the average life of a college student.