I don't think anyone is disputing the technical expertise of the employees, or their ability to do great things with animals in their care. Most critics of the zoo and the Irwins (not Bob) are simply saying there is more to them than meets the eye, and there was more to Steve than met the eye. If you want to be starry eyed and believe the media hype that surrounds the family and the spin surrounding the zoo and its place as a conservation hotspot, you are free to do so.
Like a lot of high-profile animal people, they become very possessive of their place in the system and often become very bullish towards those with less power, namely you and me... There are at least several experienced and well-meaning keepers who've had their fingers burnt in dealings with such individuals.
J