I totally agree with that. I still think Apple should allow for users to downgrade just in case. I have 3 iPad's and none of them are on iOS 8. I've done my research and watched Youtube videos.
1) My iPad 3 is still on iOS 5, anything higher than iOS 6 just kills it.
2) My iPad 2 is running iOS 7 and going to iOS 8 will impact the performance even more.
3) My Air is still on iOS 7 as it runs 7 decently. I'm not sold that iOS 8 will run things better performance wise.
Now i'm looking at iOS 9 to see if it improves performance on the Air and if it will support my iPad 2/3 and improve performance as well.
Wow same. I have been doing my reaserch. Just like you, I have nothing I keep on iOS 8 (except faimly iPad 2). From Youtube videos to my friends and the forums, they all tell the same story.
IPad Air is running iOS 7.1.2 (father updated it from 7.1 and, I got angry at him

. Mine runs with the 3 minute lockscreen glitch but, overall, it works faster and more efficent than my iOS 8 friends


)
IPod touch is maxed out at 6.1.6 (came with iOS 4.2 but, updated because of iMessage and, I had a backup already with iOS 6 [last iPod got totaled])
iPhone 4S is running 6.1.3. due to design and, speed. My friends are extremely jelous because of this one
If apple would allow downgrades, we all would be happy. They do not because, they want us to be all locked in the same iOS version. The later the iOS version, the slower it is
Now, the faimly iPad 2 is a different story. It got bricked running 7.1.2 one day. My father did a restore and, went to 8.0.2

. The thing would never work and glitched out like crazy

. Finally, one day, I update it to 8.2 and, it runs like a champ. it is faster, but not as fast as 7.x
Even with my friend's iPads, each problematic one has 8.0.2!

After I update there Air's (we all have the same models just different iOS's for work), the 7.x ones STILL work better

Would downgrades solve these struggles --> YES
Would apple let us downgrade without jailbreaking NO
Has they caused there own problem YES