Gated gear and useless benchwarming characters.

You know why it's really there? It's present to keep players occupied and feel like they are advancing towards something. if everyone had great drop rates and geared all their toons up quick, the game would become boring very quickly. They need a long string of rewards to be able to keep bringing new content. They probably time how long it will take for everyone to reach Gear 11 and plan to release new content when they think enough people have reached the zenith of the game.