All of this could be mitigated if Apple would allow downgrading the os
Indeed this is the truth.
In fact, it's quite funny when you think of how long we spend waiting for bug fixes, just to have a new version come out that needs more bug fixes.
We were trapped on the sluggish and buggy 7.0 for half a year before we got 7.1. I still remember people saying it "runs fine" and all on 7.0, which of course, it didn't. When 7.1 came out, it was very noticeable how much speed we had lost with 7.0.
The lack of being able to downgrade the software version is a major consideration for me now. I've been burned too many times, and really, for what?
Like OP, I can't help but wonder what's so much more demanding in iOS 8 that it runs so poorly compared with 7.1 (and the blazing-quick 6).
Perhaps they're trying to get people to upgrade when they can't take it anymore, then they patch it up for those who refused to update.