Crapware can always just not show a tray icon and keep on running in the background. Preventing the installation of crapware is a very, very different problem to solve than putting the user in control of the user experience.
Sorry. I was meaning more along the lines of things like Quicktime, Real Player, and other such programs the user has installed as a means to an end, but now can't easily figure out that it's always running and starts to wonder why their brand new PC is running slow...
