Creating a frontend to an existing project is much better than starting an entirely new one because all other frontends will benefit. For example with CD burning you have Brasero, xfburn, and K3B which are all just frontends to things like cdraro and growisofs. When the developers of one of those frontends needs a new feature or needs to fix something, ALL of them benefit, so no matter which GUI you prefer, they all win. Starting a brand new project that competes against something much grander (such as koffice vs libreoffice) is really just selfish in an open source perspective.
If linux and open source wants to be the best, we need to work as a community. When you make something DE centric and start from scratch, nobody wins.