Actually, this should apply to both female and male actors. From 20-30 they are typically at their sexual attractiveness peak, but from there they need to branch out as having some other value than sexual attractiveness.
Yeah, you are pretty. What else can you do? Pretty doesn’t last, so what else you got?
A lot of male and female actors figure the only thing they can do after their peak are “mommy” and “daddy”, or even “grandparent” roles. And while there is a place for those roles, to imagine that is the only thing people over the age of 30 can do is pretty weak.
Some last. Mary-Louise Parker still looks good into her 50's. She was still hot in Red 2.