The car parks in Epcot have trams to take you right to the gates anyway so there isn't any more walking involved than going to one of the other parks, plus you have the advantage that if you are watching the fireworks, when they have finished you will only have to get the tram back to your car rather than the transportation.
I don't think there is anyway to avoid walking through future world to the world showcase, as there is only one entrance to Epcot.