They do not mean much individually (I would however really enjoy to see such statistics), but I don't fully agree with the last part of your post. From my (somewhat limited) experience, most heroes are pretty straight forward to play. Sure, they're not all as intuitive as Skeleton King or Ursa, but I wouldn't say there's that many heroes which could not be played to at least a passable degree by your average public player. I guess what I'm trying to say is most of the heroes are fairly easy. Across the board win rates get incredibly skewered when you do not see your average pub stomping heroes in professional games (and vice versa), hence them not being a good indicator of how strong a hero is.
I had this discussion earlier with the captain of my clan, it's interesting. I personally don't think that the game should be entirely balanced around the professional scene, or even the high-tier players at large (hence why captains mode is great imo). I can't speak much for public games, as most games I play are lobbies - and the games I watch are either replays or progames/public games with progamers. It does make sense to balance the game around the most average rating, but also around the highest. I am just happy IceFraud is doing his thing..