Totally agree that the statue is too small. (And not that flattering, IMO.) And I take Margaret's point about why do it before he'd retired? Here's my theory: Nadal was overwhelming everyone with his clay achievements, and they felt like they should do something. I absolutely think, for example, that Barcelona named their show court after him, (Piste Nadal,) to get in before Madrid and the vile Ian Tiriac tried to cap them. Barcelona is Nadal's "home tournament," not Madrid. IMO, Paris gave him a statue, hoping they wouldn't have to rename Chartrier after him. But that was many triumphs ago.
They absolutely should. Philippe-Chatrier made the 3rd round of RG once, the 3rd round of W once, and the 1st round of the USO once. That stadium is unlikely to see a greater champion than Rafael Nadal in all of our lifetimes, and in the lives of our children. They gave Rafa a statue as a stop-gap. Now they need to rename Chatrier. I think renaming the entire city goes a bit far, though.