Club owners don't like to take risks on rookie managers, so they tend to go for already established names even if those names have a history of failure.
We're lucky to have Gibbo. He's given six managers their first jobs and on the whole its paid off; Robson, McClaren, Southgate, Karanka, Woodgate, and now Carrick. Four out of those six have been good appointments for the club with promotions, a trophy, European football, and play-off challenges. The few times he's brought in experienced managers to steady the ship or rebuild, we've failed (Strachan, Monk, and Wilder being the worst of the bunch imo).
I'd rather our club take a risk on a Carrick, than appoint a Steve Bruce.