I think the reason why it became a problem has to do with many applications, especially old ones, being written in with a "single user" mentality, not understanding the need to clearly separate system and user data. It makes sense that Administrator (or root) rights are required when you install an application, but after that it should run without needing Administrator rights.
Absolutely spot on, there bnt - my biggest peeves with Windows apps. It is ridiculous to expect admin rights to run software after it has been installed - especially as 99% of the time it is sheer laziness on the programmer's part.
I usually find that that granting write access to a few files or directories in Program Files or Windows allows the application to be run as a User account, not admin account.
SD