Why do you guys think this is going to break competitive play? You think people go into tournaments having their Pokemon know stupid crap like Dig and Discharge because there's only one copy of Earthquake and Thunderbolt is obscenely expensive? Of course not, don't be silly.
Think about it. How many TMs do you _actually use_ over the course of the game? Not many, I'd wager, and a good chunk of them that are actually _good_ can be purchased, which effectively makes them infinitely usable anyway. The rest of them are stupid stuff no one cares that they now have 80 trillion uses of like Bullet Seed and Taunt.
Even if gen 5 has its own TM list, this isn't going to be as horrible as you guys are making it out to be. So you have multiple pokemon that can learn Earthquake? Fine. Now you're saving time by giving it to those Pokemon. It's not likely that your entire team is all gonna be able to learn the same TM (stuff like Earthquake), and if it can, your team either really sucks, or you're doing some silly gimmick team in which case you have no reason to complain.
And as someone else mentioned, if this really bothers you, then only use it once and never use it again. Infinite use TMs are nothing but a convenience, but I'm curious how they're going to explain it in-game.