Do you have any idea how hard it is to change your main at the pro level. I don't, but I assume it's a doozy. Tourneys will always have Falcos, Foxes, Marths, Peaches, Sheiks, and IC's, and hell, even Samuses because M2K, Vidjo, PC Chris, DSF, Wes, Chu Dat, Husband (is he even good anymore), etc... aren't going to change characters after five years. I know Ken can play Fox now and Chu has been experimenting with Pika and Young Link, but they do infinitely better in tourneys with their mains. Azen is the exception, of course, and this is why he is so special. Thus, we don't need to see an overrepresentation of IC's at the tourney level to warrant a restriction on Nana's f-tilt and d-tilt. I believe that with perfect theoretical play, nobody would ever get hit. Thus, when someone gets hit, it is because they made a mistake. When somebody is playing IC's, they are able to make significantly more mistakes. This is a lack of balance should be corrected. Obviously, I think most people here agree that if Giga Bowser were playable without AR, he'd be banned from official tournaments. It's just a matter of where you draw the line. How much imbalance can each individual tolerate? I'm cool with shining because one shine is not insta-death, and it requires a lot of skill to shine effectively. Wobbling at this point is like pulling off a rest, but if you miss you don't suffer 200+ frames of end lag. I choose to draw the line of tolerable imbalance in front of that. True, pros don't get rested very often, but a rest with virtually no end lag is still broken and imbalanced.
I admit that I've never played against a Wobbling IC. However, I've played against people who four stocked my main, then lost when I switched to IC's.