Bitcoin doesn't let me withdraw US $ from one US bank account and deposit it in another US bank account in bulk.

Bitcoin lets me transfer bitcoin around - which is fantastic and wonderful - but it doesn't address the problem at hand.

You don't understand. Once you're in the Bitcoin ecosystem, you don't necessarily need to backtrack out into US $ anymore. I buy almost everything with Bitcoin, and shop at Bitcoin-friendly stores. Except for grocery stores. I don't know of any grocery stores yet that accept Bitcoin in my area, but they will surely arrive someday.