Generally, I think you're right. But there is quite a range even for coupes. I'm sure Porsche can afford to use higher strength steels, but the pillars on a 911 are surprisingly thin: https://h7.alamy.com/comp/B082JF/2008-porsche-911-turbo-in-s...

On the other hand, coupes with rear hatches can be particularly bad: https://www.motortrend.com/uploads/sites/10/2015/11/2004-toy...

Looking at the extremes like the Honda CRZ, it does seem to be a low priority area!