It's certainly not a DAZ limitation, it's a porn logic thing. Look at Marla - perfect exacmple of a mature woman. Skin's no longer smooth, haircut is functional, clothing is functional rather than a statement etc. How many people hate that she is a LI? Now it looks like she's dressed up to go clubbing while she's teaching - complete porn logic to win players over to the necessity of Marla for Ocean's story.
If Ocean didn't, everyone will complain about Marla's scenes as unrealistic, because what horny 18 yo guy would go for her (despite the fact Nika isn't a horny guy)? Would it be a stronger story if Marla didn't look like she was competeing with looks, but competeing with her maturity and care? I mean, that's what Amber wins on, people like Amber and Noji because other than looks, there is no teen angst from them. Attractive and over their insecurities? What's not to like?
So given that, the ageism is purely based on player expectations of what is attractive, and most players are thinking like they're a horny young MC (even when the MC isn't horny). And the players have played all the other AVN's with landladies and milfs that are 20ish and have 18 yo tenants, so I guess brain muscle memory?
About Mila - the problem isn't that she is different, but that she keeps changing, and looks unnatural, in a game where almost everyone is mostly natural and doesn't change as much. Vic's boobs in Ch4.5 and Mila stand out because they're not up to the quality we see everywhere else. Noji's changes are a complaint because they made her look younger, but no one is making their stand on that hill, because it fits the porn logic of every woman being attractive to the player.
Consistency is the thing. I also don't think it's necessary to fix it, we can't unsee Ch1 Mila being different from Ch5 Mila, but there's hope Ocean will keep things consistent from here.