I think the shy girl archetype is even bigger than the MILF one. A general recluse that slowly warms up to the MC has always been something I find adorable. As long as they keep some of that shyness and not turn into some sex-addict once you start a relationship with them.
Adult Visual Novels would improve immensely if they just stop with the obsession of banging grandma.
Of course that would be hard since you can only make grandma in Daz.