I agree on some level that winner should stay with their character in tournaments until they lose, but that's never been a rule of arcade MK games, and we play the games by arcade rules. I have repicked before in tournaments myself but never as a counter because almost always the other person never changes their character against me, no matter which character I use. For me, it's about variety, as I understand it probably is for some of you. However, when you're playing in a tournament for money, and you pick your character first, under the rules where you can change your character, expect to get counter picked. The issue of repicks has come up more and more, and I talked to Phil about it at great length. We have yet to come up with a solid solution, other than if the winner wants to change characters, they must select first to allow the losing player the chance to counter pick, which they fully have the right to do if they lose, in any game. If they only play one character, it doesn't matter, except it can be argued that they should have the chance to play against a winning character until they lose the set, or can adapt. The only thing repicking does is possibly expose who has more or less range in the game in general, or the limitations of someone who can only use one character.
For now, I suggest if you want to avoid being counter picked, don't pick first, and honor the unwritten rule of no repicks until you lose anyway. No one should be complaining about being counter picked in a tournament, that's basically saying "I want to use this character just to use them, and it's not fair if you pick a character I will have difficulty with." That's why there are tiers, players have mains, and there are rock paper scissors factors for characters. If the first match of a UMK3 tournament I'm in, the person runs to Kabal, I know what characters I should use against him, even if they aren't my personal best, and I will pick those characters. Beyond that, if I won the first match, and picked another character to keep the Kabal player guessing, that might be considered unfair, since they wouldn't have the chance to beat my first character with him if they wanted to try again, but that's the rules we've used for 9 years now, and only in 2010, when the competition has stabilized at a legitimate level, has this issue come up, so maybe it's time for it to come up. Banning things has only come up this year as well for UMK3, and the game's 15 years old.
Otherwise, all I have to say is, don't make me resurrect my MKII skills for Winter Brawl.