This and only this is the main reason why I prefer Full writable instead of UEM tooling (whichever tool you may use).
There are also applications that drop a huge amount of settings in the Localappdata folder (Google Chrome being the most known) which will cause applications to start up very slow if you are to use UEM to capture preference settings.
The only option you have is to use the UIA + Profile option as it would allow you to capture anything witin the Users folder. I think that your profile will be corrupted if you were to only use the localappdata from the writable and use a roaming or mandatory profile for all other info (not 100% sure though).
And to be honest, installing en entire application in the profile is plain bad programming. There should always be an option, with every program, to install it into the program files folder.
You could however use the full writable with UEM and if a problem exists just remove the writable and recreate it, settings will be preserved by UEM.
I agree that putting your entire application into Local AppData is bad programming. Unfortunately, even Microsoft is content on putting app binaries into Local AppData folder as evidenced by their UWP apps in Windows 10 and .NET Framework based click-once applications. It seems like more and more app devs are trying to get around the fact that users may not have admin privileges to their desktops.
So it seems the only viable option moving forward is UIA+Profile for now.
I think so yes.
Normally though programmers do tend to get past the "not being an admin" thing with installing apps in the user profile but normally (at least most of the applications I have seen doing this) also have some sort of admin installetr available that does install in Program Files. It sometimes takes a bit longer to get this installer but might worth a try.