Why don't I rent a car? Why WOULD I rent a car?
I park my car in the cheapie lot ($4/day!!) and take the shuttle to the airport. Once I give my bags to my friendly Southwest agent, I am hands-off until I pack them post-bedbug check.
Arrive at MCO, cross to B-side, down the elevators (can you take the escalator down?) and then follow the signs. On the bus, where your biggest decision is how close to a monitor to sit. Someone else handles the tolls, the traffic, and the directions. Arrive at Po'Half, check in, and head to the room for the aforementioned bedbug check. Drop our carry-ons, and off we go.
All week, all we have to do is follow the signs. Marathon weekend, half the roads closed? No biggie. Want to start at DHS, have lunch at Cap't Cook's and spend the evening at the MK? No worries about where you left your car.
I pay for the busses, boats, and monorails, plus DME and luggage delivery, in my $169 "value" room rate. I don't spend $3500 for a week at the Poly... I guess I could, but it would be an annual trip, instead of several as an AP-holder. We get on that shuttle at the airport parking lot and have no worries, all week. If the worst thing I have to fuss about is standing for an 18-minute bus ride, I am golden!!
ETA: We stayed at a hotel with mandatory valet a few years ago. Talk about a hassle... I waited longer for my car than I wait for a bus, 95% of the time. Also, we DID rent a car at the start of one trip last year - went to Universal, then drove to MK for the night before heading home to Pop. It didn't really save us time on the WDW end of things, not to mention, I am not a good tired driver, and we leave those parks EXHAUSTED, so it's best that I let someone else do the driving!