Apple and Google are billion dollar companies as well, yet they discover many issues on global rollouts too. Which in regards to Apple is even more suprising than with Microsoft or Google, since their software run on their very own hardware, which has a very limited set of components to choose from, unlike companies like Microsoft and Google whose software have to work on all kinds of different hardware specifications.
I'm not an insider, but considering the fact that the issue only appeared for those who have their devices enrolled in a company envorinment and only in combination with updating from WP 8.1 DP Black to WP 8.1 official Cyan, it most likely is a change in certain parts of the firmware. Hence it couldn't be discovered before the rollout, since 8.1 DP ran on Black.
Seriously, guys.. All this "Mimimi, I don't get the update right now" whining is overly exaggerated behavior. Do yourself a favor and read through some forums to see that issues like that are common on BBs, Androids and iPhones too. It's absolutely usual to see more and more bugs popup the more people use something in comparison to limited beta testing stages.
Not to mention that it was your very own choice to participate in the 8.1 Developer Preview. It was clearly labeled as beta and you cannot expect a beta to run fluid, stable and without any issues at all. That's why it's called a beta. And it has the name "developer preview" for a reason.
If you desperately want the update now, roll back to 8.0, which is an easy task and get your update. Doesn't apply for the 1020 though, since it's not yet available afaik. But this again is something you can barely hold Microsoft responsible for.