The benefits are stright forward, once you (or your company) understand what Qubes can give you…
Other obstacles we have identified:
- very low (5-10 times less) ‘battery time’ comapred running windows on the same hardware.
- hardware compatibility. They simly can’t use the latest modells from the used vendors, but have to pre-test/certify every new model by our own. - this also brings in a huge political conflict with the hardware wendors.
- nearly all of the endpoint management software/systems out there is for Mac/Windows. - and again a huge political question to move out from the current ‘partners’
But frankly, the biggest obstacle is the human (the user) factor. They simply don’t like to use (and learn!) such exotic desktop. They are obsesses with the ‘fancyness’ of using a Mac, or they simply stick to the windows no matter how terrible it is in practice.
and just for the context:
I’m personally using Qubes since the very firts beta release. That’s 10+years now. 
means this is my main desktop for work (where allowed) and at home.
also there is another topic about this question: