Which is no solution at all. First, family sharing is only partially functional, forcing many of us who have been using a single account for years to stick with it. Second, my kids are 3 and under. It will be years before they will have their own devices. There is a huge window of time when a full kids or guest mode is appropriate. Third, I will always have an iPad of some sort that is shared among the family because it is so convenient to keep one in the kitchen for reference, music, video calls, etc.
With iPad sales forecast to fall by as much as half this quarter, Apple ignores this reality at their own peril. I wager that we will see some sort of multi-user support in the next 1-2 years, maximum.
I'm not disagreeing with you, I have wanted that feature for a while. But I also wonder how multiple user accounts would help you in your use case anyway?
I mean if every user is still tied to your/a single AppleID (Apple is going to use AppleID's for this feature if they ever release it, because iCloud and the App Store are based on it) then how does that solve your issues? Your kids will still be on your AppleID and all of the same problems will exist that you described.
My kids are 3 & 4 and I made AppleID's for them. They each have a hand-me-down iPad 2 32GB that is "their own." from my wife and I, who are on an Air and Air 2 respectively. I have set restrictions on each of their iPads as I deem appropriate, require them to receive permission for App Store and IAP, and they still have access to all the educational and kid apps I bought for them previously under my AppleID. Also, this has freed up my wife to use her own AppleID exclusively on her iPhone and iPad now. She also gets approval rights for App Store and IAP our kids try to make.
It has really simplified things, because now each device can just sign in once to iCloud and be done. No more complicated setting with having to turn off iMessage, log into iMessage, the App Store, and iCloud with different AppleID's, etc.
This is why I think that Apple's Family Sharing solution is really the only way to go. Even if iPads got multi-user accounts, Family Sharing would have to be used alongside of that in order for it to be of any real use.
The only real "bugs" or lack of functionality I am seeing so far with it, is that some apps haven't been upgraded to be compatible with it, such as two my wife uses, Pinterest and Instagram. There are a few of the kids' educational apps that aren't updated either. The biggest irritant with it is that the auto-update feature stops when it hits one of these apps, so my wife (who is definitely not tech savvy) always has 25+ updates because Instagram is blocking everything, for example. I'm confident this stuff will melt away as time passes.
All that being said, I can possibly see the big iPad Pro offering this feature, if any iOS device will. I expect this to be priced equal with the entry level MBA, so starting at $799 probably for a 16/32GB Wifi.