Balancing is hard when there are as many characters as the Smash games have. In Melee Sakurai stated that Ganondorf was a weak 1 v 1 character but he turned out to be one of the best in the game. Just as Sakurai now seems to state that Little Mac is not an aerial fighter. It's very hard to predict what makes a character good/bad or what the meta game will revolve around, I bet Sakurai didn't count on the Shine (Fox/Falcos down B) being the most broken move in Melee but through several AT's it became an insanely powerful move.
Don't be too sure that the new Smash will be balanced and all characters will be useful. Even in Project M, which is considered a balanced version of Smash one could make the argument that even in that game there are characters that have a really hard time. Ganondorf vs Fox is, for example, still a match up that is very uneven and in Fox favor.
Of course I still have hope (altough I might sound a bit cynical), but my hopes relies mostly on patches to be entirely honest. Then again, in my opinion the most important thing is to get rid of true chain grabs and such things that plagued Brawl a lot. Pikachu could, for example, chain grab Captain Falcon up to 100% (and Falcon can't do anything about it). Now that is bull****.