You're right - obviously you want to start from the top down, not work bottom up.
The thing is though, it's not like a university president needs to hire the AD or be the President's "guy". And there are plenty of ADs that inherit coaches that they are a-ok with. The obvious point is that if you have the right people in place, it doesn't matter. Purdue's been slow to react in general - nobody wanted to be the person to shake things up. Hazell has basically done the same stuff Hope did, Burke has let things remain constant and Daniels let things remain constant.
Having some longterm plan is great in theory, but if it holds up the process, it's not. We've already waited too long on Hazell and you can argue the writing was on the wall for Hope as well before things were done (and not that he should have been fired a year earlier, but if you knew you were going to fire him midway through the season - the firing/hiring process seemed to be a disaster knowing they had a few months to work with).