I don't understand windows
before it was never a concern, then they try to follow the more linux model that has a bit more security, or at least it is more in your face, and now you basically always have the prompt show up.
most updates and installs need admin privilege, because they are changing/accessing files that are protected (such as if you save the game instal in important directories like the program folder, you need admin privileges for programs to go in there). same thing happens with most program, if you save a word document to desktop, no pop up, but if you also try to saveas in the program folder, the computer won't allow it, unless you run in admin mode with the program.
so maybe now there are files being kept temporarily somewhere in key system folders such as the appdata folder or something, which means now it is asking for admin privilages.