KDE has an outstanding advantage of loose coupling of the various parts of it. So, you can run KDE applications in a semi-standalone mode. This is directly related to the sane component architecture and simple development model, I'm sure.
As for "better apps" - Konqueror is sort of slow on old hardware but otherwise is (IMO) the best browser around, with transparent file management as a bonus - KMail is a fine little mail client - KNode is a very adequate newsreader - KDevelop is a nice compact development tool for the environment. What more do I need?