For me disgaea doesn't demand ones fanatiscism, it earns it. They suck you in with their quirky characters and dialogues that completely breaks the fourth wall and leaves a gaping hole throughout the entire game. The game also has a lot of other quirky features, example being able to make changes in game like enemy levels from the senate and if they choose to vote against it, you can always use more medieval ways of persuasion, and if you ever lose the vote to remain the main character, then its game over. Then the gameplay takes over.
I love Disgaea! 4 is really good IMO, it's a refinement of the series.
There is something that I find relaxing about the pointlessness of it. If I get home I might just grind an item world for an hour to wind down.
It also helps the humor is really good :P