First off, the BPillar does suck, but it wont be noticable like it is on the Mustang. It wont be body colored, it will be blacked out.
Like this
Not like this
Ok, now for the reason.
GM and the Camaro team is working HARD to reduce the weight of the vehicle. Like I has said MONTHS ago, they are working to cut every ounce of weight they can to get this car under target. If they were to have a pillarless coupe, they would have had to add hundreds of pounds of structural enhancements to keep the chassis stiff, keep side crash standards up, and not to mention meet FUTURE crash standards which are going to increase.
For those who forgot, one of the 400 reasons the 4th gen was killed was because that the A-pillar, (the first one) was angled so sharp that it was too close to the driver's head, and that IF the Fbody was going to continue after 2002(if GM didnt kill it) it would have had to be on a totaly new chassis.
Adding the B-pillar adds tons of strength to the car and stiffens the chassis up to make sure we have a great platform to build our dream car off of.
Only 2 cars have a pillarless design, one is the CLK which is going to be moved onto the new C-Class's chassis soon, and the Bentley Conti GT, which costs 1/4 mill and comes in at a Suburban-esque 4500lbs, if not more.