I suspect there's a some middle aged men here who can't stand that some snot-nosed kid of 30 got this job 'based on his name'. Bet you've seen it happen before and it bugs the hell out of you.
Well, perhaps that upsets our sense of propriety somewhat but I don't think that's the primary reason. Most coaches hired in the Big Ten are veterans who have paid their dues, have taken their lumps, and have a considerable amount of trial and error in their backgrounds. Most of them also have a record of accomplishment. In short, Big Ten coaches typically have learned a lot before they arrived here.
The closest to Pitino in the Big Ten ranks would be Chris Collins, also the son of a famous coach, but Collins is 40, has been assistant coaching since the late nineties, was with Duke for over a decade, and also was an accomplished player in his own right (former IL Mr. Basketball who played at Duke). I think it is also fair to say that Collins enters a program with lower overall expectations of performance.
Pitino has little time as a coach (even as an assistant) and to my knowledge did not play the game at any advanced level. The last factor could have some relevance in how he and the players think about each other.