We always stay at BWV when we visit WDW and only get a car if we will be spending part of the time off site visiting other locations in Florida. When we have a car, we use it to drive to AK, DD and the MK resorts (for dinner). We walk (or boat) to EPCOT & the Studios, and always bus to the MK.
FWIW, renting a car for the two of us for a week is often comparable (or even less) than the cost of a RT (MCO - WDW) in a towncar. We won't do Mears - takes too long, LOL). We may try the new complimentary Magical Express, though. Maybe the "complimentary" part will take the sting out of the time I anticipate it will take to get to the resort and then back to the airport.
Anyway, I like having a car at the BWV to drive to some locations, but you need to know that self-parking at the BWV can be a royal pain. Too many people use the BW lots to go to EPCOT. It is often difficult to find a parking spot in the late afternoon/early evening. (The lots clear out right after IllumiNations). I wish the BW management would reserve some parking for guests of the BWI/BWV hotels.
All that said, you absolutley do not need a car at BWV, but it can be very convenient if you plan to spend much time at DD, a waterpark or eating at any of the non-EPCOT resorts.
Best wishes -