You don't need hit or expertise im most situations. Some tanks switch over to some more hit or expertise for some heroic encounters to help beat stuff faster, but in most cases it's not needed. Only exception is hit before patch 4.1. if you are the only one who can intrrupt something. But even then I would not advice to cap it via normal gear but to try to get it with food, elexiers, trinket change or a switch of single items for more hit.
Taunt does not miss anymore, interrupts will not miss after 4.1.