I think it is very important particularly for users who use their computer only for daily office/business/school routines. Mostly these users aren't computer savvy and any changes they may invoke accidentaly in their desktop or favorite application will surely piss them off. I personally experienced such scenario when I eagerly installed Kubuntu and Ubuntu in my friends' computers only to find out they were calling me very often because something has changed in their computers and they couldn't remember what they did.