I know of some reasons and those ar dogmatism and ideology.
We seem to be in a position of understanding that while new - or existing - predators might theoretically wipe out the honeybee, there is no reason at all to think that is a threat. And that most (99.5% was it) extinction causes are external to the species - that is species don't often (understatement) evolve themselves, as it were, to death.
Back in the world of what actually happens, some of us understand that natural selection is the tendency to propagate much more from the fittest, resulting (through heritable traits and qualities) in the best of the present genes making more of the next generation than their competitors; and that this is necessary in order to stay ahead of the constant evolution of their predators - a term that includes micro-organisms and parasites.
And that that means that any beekeeper who doesn't do the same will have natural selection do it for him - by deselecting his bees.
That's the reality. And the only bit we have to think about.
No Mike, no. You better keep up with the latest research. Here is the stuff that has been found out in 2014. Ten pages. Interesting stuff among it.
After this discussion, I was interested to read BlueRidgeBee's Notes from a talk by Dr. Jeff Pettis, Beltsville Bee Lab given in North Carolina. From the Q&A: