Whilst I'm not against the idea of appointing someone who has a coaching background, far more is needed to be in charge of a Premier League club. Managing egos, having the respect of players, making tactical decisions during games, attracting quality players to the club, keeping quality players at the club.
Maybe not dissimilar to Keith Burkinshaw, who had a coaching background. Unfortunately, that wasn't enough.
The other thing is that, if he was such a great coach, why did Moyes not take him to Old Trafford?
He's going to have to hit the ground running, and that's the understatement. Unfair maybe, but nobody'd forced him to take the job. He probably thinks he has nothing to lose, as he hasn't got a reputation, except in the lower divisions. He probably thinks at the worst, after he's been sacked, he'll find it easier to get a job later with West Brom on his CV.