We used to drive everywhere but MK. Last trip we drove to MK every time, too. It's easy to hop a monorail or ferry, since they run pretty continuously, definitely more often than the bus. The tram is usually right there when you park, and they run very often back to the parking lot at the TTC. We've gotten stuck waiting for a bus over 45 minutes. I have arthritis and that standing in line killed me. Plus standing on the bus is harder than standing on the monorail or ferry for me.
The walk to the monorail or ferry from the front entrance of MK is actually shorter than the walk to the bus, especially if you're at the further bus stops.
I know the mantra has always been to bus to MK, but we went against that philosophy and prefer it. Next trip we'll be at Fort Wilderness, so we'll use the boat. No decision necessary!!