Sorry I think you're missing the point of what I'm saying. Of course it's understandable, I've already said that. In fact it's more than understandable, it's sensible, necessary almost.
You're saying that we should employ coaches based on their coaching ability rather than ex-players. I'm saying should the same not apply to the coaches the manager brings then? You've just agreed that manager's don't employ staff because they think they're the best, they employ them because they get on (the 'worked successfully' bit is a bit of a stretch, seeing as managers carry on doing it even after repeated failures).
The point is, if the manager can employ people because they do things the way he likes, then why shouldn't the club? They believe that ex-players will be aware of how the club wants to do things and will provide continuity regardless of who the manager is so they give them jobs. Either just give jobs on merit and say to the manager sorry but i'm not sure this lad you've been mates with since you were 6 is the very best coach available to us, or accept that there are differing reasons for people being given jobs which aren't always because there is no way we could find anyone better.