One could say while DF has pants-on-head retarded dwarves, MC has pants-on-head retarded fanbase, but lets not go into that
But yea, Notch didn't put a whole lot of work in minecraft, ever really. When he stopped updating he was probably comming up with a way to work less and earn more money. Thus he got himself a group of developers to work for him, enabling him to churn out mini releases faster and gain more monies. When people get tired of MC, he'll probably come up with something else to make monies. If you look back at notch's past works, they were all simple games like flight simulators, in which he took an engine and simply worked on it.
Now DF, instead of relying on the nagging factor of control a kid haves over their parent's money, or creepy older people with nothing to do, survives solely on the mighty coding skills of toady one and the good will of its undying fanbase (seriously though, this community is considerably old), and it slowly but surely attracts new members over time. People don't donate because they want a gimmick update involving a new area and more easter eggs, they donate so DF can become what Toady wants it to become, which is an awesome, incredibly detailed interactive fantasy history generator.
I do not deny the fun MC can proportionate, but its more of a minigame kind of fun, once you've been there, its done, there's nothing to call you back inside.