Update: As of this morning, now all 5 of my Microsoft accounts have the change implemented. My parent's accounts also reflect the change as well today. This doesn't bode well for my hopes that the Quick Actions location change will be reverted soon like it was in the past. If memory serves, when this happened before, it was reverted within a couple of days, so (fingers crossed) there's still some chance that MS is reading this thread and hearing the overwhelmingly negative feedback. At the very least, I'm hoping that a feature will be added-in that gives us the choice of where we want to put it.
As a former IT person, I understand that some changes have to take place because of other changes or additional features coming down the pike. However, usually, there is much consideration towards Accessibility. Trust me when I say that is a very important part of why there is beta testing. What makes this particular move odd is that it is a really impactful Accessibility change, meaning folks have to move their mouses a significantly longer distance to take the Quick Action. That type of change is typically shot down because of exactly what users have complained about: Takes much more effort/time to process email, specifically when you have tons of email each day. This is especially true in today's world of *huge* desktop monitors and excessive screen real estate. So it's just really odd the change happened at all (both times now). Maybe MS is counting on the fact that Gmail users have proven that the new Quick Actions location is usable and (in some cases) desirable as one gets used to it. Not so Microsoft. After reading all of these posts, I would wager that a good majority of your OWA users specifically stay with MS over Gmail partly because of this feature.
Finally, another user posted that if you remove the Quick Actions, they revert back to where they were. It was implied this was the case if you add them back in. This is untrue (at least with me). I tried in all 5 of my accounts on 4 different browsers.