They're doing exactly what they said they were going to do for a long time now. They want all apps to work together without conflict and increase the security of the OS. The Ars Technica review gives good insight to what Apple is doing and why.Man what is it with Apple?
Developers have had a long time to prepare for this. Adobe is clearly the worst offender. Mavericks was supposed to be the last OS to support JRE 6 yet it still works in El Capitán. It will interesting to see if it really is dropped in 10.12.
It wouldn't bother me to go back to Yosemite except that I like the way 10.11 works with iOS 9.
USB is the only surprise. What the hell happened there? Was it the firmware upgrade? If it is going to take 10.11.1 to fix, it needs to happen soon.
So, no one really needs OS 10.11 yet.
Windows is still worse as all of the "how do I get the drivers working" threads remind us.