All great points.
You mentioned her type of fanbase:
It has been argued in this thread that number of web searches reflect popularity. While there are a large number of web searches for Sharapova, the top ones are: hot maria sharapova; maria sharapova pics; kournikova sharapova; photos maria sharapova; maria sharapova pictures; maria sharapova video; fotos maria sharapova; maria sharapova boyfriend; and, maria sharapova bikini. I think that makes it obvious what her fanbase is like. Of course she does have some normal fans who are interested in her tennis, but as far as web searches goes, it is the horny little boys who dominate.
I've looked up several other players, and the top searches for them are almost entirely tennis-related. Even Ana Ivanovic, who is also quite attractive, has the majority of her searches related to tennis. Not one of the top searches for Sharapova has anything to do with tennis. This really underscores your discussion of having a large fanbase vs. being famous, and her lack of a cultural impact. It is actually kind of sad that all a large number of her fans care about is how she looks. I am glad for her that she has some fans who are legitimate tennis fans, and like her primarily for her game. You know the rest will bail if/when she gets older, gains weight, becomes less attractive, etc.
Oh no I've searched for pictures and videos of Maria. I've also searched "Maria sharapova boyfriend", I'm clearly not a real fan. And all this time I thought I was one of her biggest fans.