If Smash didn't support GameCube controllers what would people do, never play it in a tournament? Wrong, they would come up with a solution.
What solution? Barring someone inventing a way to make it work, there isn't one. If we had no other choice we'd just have to deal with the problems, and it would suck.
Asside from that, why does it matter!? Are you going to go to tournaments??? Also, Sakurai had the insight to give us a wired option. It's obviously better to do that than ANY other solution we could come up with. It's so obvious that the best route for tournaments is to go gamecube controller only.
It isn't a moot point because you shouldn't ban something just because it supports wired controllers if it may work properly.
YES, you should in order to ensure that there are NO complaints and problems. Have you had to deal with a tournament dispute before? Have you had to deal with all the stresses associated with running a tournament? I have, nothing large mind you, and it's actually pretty daunting. It's much easier, smarter, faster, and just way more efficient to ban wireless. It's REALLY not that hard to get a gamecube controller.
Also at E for All, E3, and other places there have been TONS of Wii's in one area without lags, desyncs, disconnects, etc. At what point does too many become a problem? I haven't seen any solid proof because while one guy complains about the PS3 having issues it is KNOWN to desync even without other PS3s in the room. I've been in one place with a ton of Wii action going on with no problems.
Read M3D's post. That is scientific data. Also, MLG is taking a no wireless policy in general, so people would complain if they could use wireless wii motes.
Secondly, didn't Nintendo provide the wii motes at E for All? If so they were pre-synced and people just traded them off. Not to mention that it was 4 player ffa for 2 minutes on a game people were playing for the first time, so it is a good chance that crossing simply wasn't reported.
Thirdly, just how many booths were there? What are the numbers we are looking at? You say you have proof, but I really doubt you could give me a solid number.
You have to take ALL of these things into account, not just some ideal situation like E for All.
I've been in one place with a ton of Wii action going on with no problems.
Unless it was in a place saturated with 50+ wii motes it isn't really relevant.