Although I have played and enjoyed some of the crunchier games out there, sometimes they just start to feel more exhausting than fun. I’ve also found it hard to get players to buy into games where you have 20+ different questions/choices during character creation.
Ontop of those, sometimes a systems release schedule has made me stop wanting to run the game, I am personally not a huge fan of games that put out 3+ books a year,
How much is too much for you/your table?
This issue is probably the most draining for me. When I ran Shadowrun I warned my players that it was crunchy, and they promised me that they would learn how to play their classes. The streetsam did –the decker, rigger, adept, and technomancer did not.