Personally, I'd just as soon have the B pillar to give the window more support. In fact, I'd prefer the window had a frame all the way around it, a la the aircraft-style doors on the Ford Thunderbirds of the 1983-1997 era.
When I still had my '70 Challenger, the front windows became looser as the years went by, mainly because of the suction effect created whenever you roll a window up or down while the car is in motion. Eventually, the hairpin-shaped brackets (which were the only things actually holding in the front side windows) broke and believe me, it was impossible to get new ones. Finding none in junk yards, I had three different machine shops try to make new ones for me, with little success. Texas Auto Glass made a fortune off me, as the driver's side window often came off its holder on my way to work and their shop happened to be right on the route. (They actually got so good at fixing it that they could pull the door panel off, remount the window on the holder as best they could and get the panel back on in five to seven minutes -- all for $22.50.)
Frankly, the B pillar issue is so unimportant that I'm shocked at the amount of time spent on it. The pillars we've seen spy shots of appear much narrower than the B pillars on my 2000 Mustang, and those certainly don't do anything to add to or detract from the appearance of the car.
Also, in all the years I had the Challenger, I don't think I EVER rolled down the back windows, except possibly when cleaning them. Only three or four times were there ever people in the back seat, and they might have rolled them down. After all, part of the reason for having a two-door car is to discourage people from wanting to be hauled around in the back seat.
