Consider two candidates for an assistant coaching position: Candidate A has the most football knowledge and coaching skill, but is an arrogant $&@#(@#& and is almost intolerable to be around for both coaches and players. Candidate B is a very solid football technician, not quite on par with Candidate A but still very knowledable and skilled, but is also a great role model for the kids and will be an asset in recruiting.

Are you so confident that "coaching ability" is the most important that you would hire Candidate A every time over Candidate B?

If what you're saying is that it doesn't make sense to hire an UNQUALIFIED coach just because of some other factors (parents are big boosters, race, religion, etc.), then I doubt many people would disagree. But once you assume basic levels of qualification, its pretty hard to put everything in a rigid hierarchy and say which things are absolutely the most important. Each candidate will bring positives and negatives, and you have to weigh everthing together and make the decision on what will be the best decision overall.