It's not so much questioning how he got the job but the smug, sneering attitude and assumption that he will fail. Nobody was saying that he is an intelligent, educated guy who obviously impressed the Bayern hierarchy during negotiations.
I'll admit that I have reservations about him taking on such a big job at a club where managers are not always backed but I think he has a chance to do well. Bayern have some very good players and success for them next season is probably winning their league and qualifying from their Champions League group whereas in the past league success was assumed and anything less than a European semi-final was viewed as poor.
I think Bayern are gambling on VK's potential based upon his personality and the football style he demonstrated during Burnley's promotion season. Being seen as a Pep disciple is probably also a factor.
I don't think VVD or Maguire will match what VK has achieved and the potential he offers but, if they move into management and have success at lower levels I would not begrudge them a shot at managing a European giant.
One prediction I will make is that VK will be at Bayern longer than Shrek will be at Plymouth.