That's because you drive it like a sportscar. Perhaps those owners that don't, or maybe can't, don't appreciate how hard it can be made to go. A lot of people didn't rate the 4200 as a sportscar but I know quite a few Supercar drivers that do now. It's great fun educating them!
I guess we are down to personal definitions here. A sportscar to me has to be light, smallish but not necessarily massively powerful (due to lightness) although lots of power is fine
. I think the GTS is closer to a "supercar" than a sportscar. It has, drama, noise, is relatively rare, grips and handles well, and is quicker and more powerful than many sports cars. My 997 turbo is supercar quick but doesn't have the drama of a Lamborghini, Ferrari or many maserati so to me is more of a sportscar that just happens to go like a supercar.
.........In fact, the more I think about it, it is a GT car! Big, comfey for transporting passengers and luggage huge distances, but can show many sports cars a thing or two if flat out along a twisty road (although not it's not it's preferred manner of being driven). The clue is in the name....