Quite a loaded question, eh?
The answer is most likely similar to other similar questions. What holds us back from exercising? From taking our vitamins? From eating healthy? Or any other similarly-sensible, good-for-us but no-fun types of tasks or projects.
Inertia. Or the absence of a concrete action plan. Or lack of proper (strong enough) motivation. Or possibly its the handy-dandy rationalization (I don't have the time/need/money, etc)