A common phrase in IT, usually uttered when someone tries to do something which you _know_ will end badly, because they're trying to change something that doesn't need changing in the first place.
The expression also causes us the necessary frustrations: people hold on to (very) old versions of software (Internet Explorer 5, Windows 98, ...) because "it still works". How are we to use new technologies and methods, when there are still a lot of end-users that don't make the necessary upgrades to take advantage of this?
In the never-ending browser-wars, this is just about the most frustrating thing -- gettings things to work in all versions of the software -- even if it is over 8 years old and totally outdated (IE5). Why should we keep investing in learning new techniques, fancy new technologies and the likes when it won't work on nearly 10% of all users?