Why do you keep releasing new champions, RIOT?

I feel as though releasing more and more champions is severely hurting the health of the game. As each champion becomes released, relationships between items, different champions, and the meta becomes significantly more complex.

Examples could be that Ahri and Fizz, untouched for a while, suddenly become too popular for your tastes. Oddly enough, this happens after you nerf the other assassins.

Lux, Zyra, Annie and Fiddlesticks are becoming popular supports after you nerfed traditional supports across the line.

Do you have a plan in place to compensate for this? If not, when will you stop creating champs? At some point it will become too cumbersome to balance, no matter how many are on the live team. Is revenue from new champ releases that vital to keeping RIOT afloat and innovative?