Earlier quoted context omitted.
And maybe dim the background, as wel as giving information about the creator of the application and if its codesigned. oh wait, that was too obtrusive and annoying
Not sure if you're being sarcastic about how users feel or about that kind of configuration for UAC, but personally it's one of the many things I dislike when I'm on a Windows computer. For power users it's annoying and disruptive. For users that might benefit the most from it they quickly learn to press ok always whenever they are prompted for something, no matter what it's asking. In my opinion, an ideal OS would h…
Let me stop you right there. As a sysadmin, UAC is both effective as it is necessary. I absolutely don't want any application a user can launch with a mere YES/NO prompt but proper secondary credentials, interactively or by some nefarious app spawning other processes, to have the ability to gain an administrative level of access over the local machine. Unless it's absolutely necessary (which in most cases, it's not!).
"Power Users" are, in my experience, an annoyance at the corporate level and especially at home when they bomb their system so badly that it requires reinstalling the OS every few months.
However your other points raise a good standard and I'd like to specifically mention one I really want to see in Desktop OS's. That app sandboxing for every "feature" accessed should be a whitelisted (by asking for permission) endeavor. It should request access to the file system (only for those directories in its specific needs), calendar, contacts, network access, looking into other apps (themselves or their access to the file system), network access, etc.