Nobody is complaining about whether or not captain falcon is viable. We have someone who placed 5th at EVO with a pikachu, so yes, a large amount of the cast is viable. Fox isn't even the most successful character; studies have been done and fox is not nearly as rewarding as people think. Unless you consider mango a true fox main, no fox main has won a national recently other than leffen. Mango does prefer fox but even then, there are simply so many top tier non-fox players that the 20XX conspiracy will not happen for at least quite a bit of time, if ever. PP mains falco and marth, armada peach, m2k shiek and marth (his fox has not come out recently), Hungrybox jigglypuff, axe pikachu, etc.
L canceling does not serve as an arbitrary feature; it's deeper than people think. Try mindlessly spamming aerials without l canceling - it's hard. L canceling is made to tell your brain when you land. While this technique should definitely have been made more accessible, you cannot claim that it was an arbitrary skill barrier. It ensures that a player is not dependent solely on timing because he now has to use the visual aspect of the game. I honestly think playing at a higher level would be harder without l canceling and with auto canceling in its place, but that's just my theory.
That being said, smash 4 is its own game and we should embrace it for what it is.