I do rent a car and there are a couple of things to consider.
One. I NEVER drive to MK. By the time you park, take the tram or walk to the TTC, catch the boat or the monorail to the park it would be quicker to take the bus. A taxi is only going to get you to the TTC so not much time savings for your money. The Disney buses drop you off at the entrance!
Two. If you stay till closing and leave with everyone else the traffic coming out of the parks can be a NIGHTMARE. It is made worse by people who realize that they need to exit right and are in the far left lane. They will then just ZOOM across 4 lanes of traffic. This is NOT an occasional occurance. I see it at least once a day at Disney. Are these folks allergic to going ahead and turning around? If I know I am staying till closing I will often take the bus just to let Tyler deal with these people whose Driver's licenses should be confiscated.
Three. The buses drop you off much closer then the trams at all parks.
Four. And this is a personal preference. I don't like taking taxi's.
Five. The commute is the same distance on a bus. At the All Stars the buses only make one or two stops so.... that really isn't bad, the worse part will be waiting on the bus. It always seems like forever, but I have timed my waits numerous times and I agree with Tyler, the wait is never as long as it seems. (The last time I stayed at OKW I was waiting on the bus when a family showed up. Bus came, we got on and they were VERY upset with the bus driver. Claimed to have been waiting 30 minutes. WHERE? Time in your room does not count! They shut up when I said to the driver that I got to the stop at 3:15 and it was 3:30. They knew I was there when they got there.)