Oh fine, I'll come out of the closet and say making it a convertible makes it more appealing for us to purchase as a "fun" car. I might take it to a track once in awhile, maybe an autocross or two, but primarily it's for enjoyable weekend driving with my wife. Open air adds to the fun factor for plenty of folks. Personally I'd prefer a compromise... a targa top.
I'm glad it's designed primarily as a coupe, so the focus can be on handling & structure... the guys who track it frequently will still get a car designed for that, and I appreciate that.