I for one am of the opinion that the power creep is a good thing generally, but it must be restrained so as not to get completely out of hand. It isn't fun to watch your favorite army be turned to dust by every new army.

Banning certain things IS an effective tool for fixing a game! While a codex in general might be strong, it may also have an outlier so ridiculous as to force every army to bring a tool specifically to counter it, if they even have one. Does that simply change the meta? Well yes, but it also prevents a person from dominating a tournament just because he has the one power unit.