It seems like wind load is the only major con for hard-sided that people have found (other than weight). Is that right? It seems like weight could be taken care of with a bigger truck (350-450 or equivalent).
As for lowing the height of a TC box, that sounds good in theory if you're a shorter person (like me), but it would also lower the (already low) cab-over height to make it even more coffin like.
One of the best modifications I've done is to add hydro-assist steering. Besides making turning big tires easy, a side-benefit of hydro-assist is that it is the best steering damper around.
Our camper is around 11'6" tall. It is unaffected by side-winds by and large. Adding hydro-assist is going to be an early mod in all future trucks where possible.
Regarding the topic of this thread, it always surprises me that the market for pop-up campers is as large as it is. For camping for an extended period of time a hard side camper has no downsides and numerous positives as others have mentioned already.