There's supposedly an increasingly common practice of starting early, so the wrinkles in those areas don't ever develop in the first place...

I imagine it also prevents a more abrupt change later on if you're intending to do it. Going from an expressive wrinkled face to a paralyzed one in your 50s would be much more jarring for your peers, than just lacking expressiveness much of your adult life.

It's all a rather weird form of vanity to me.