There's not much point for a development/test platform for the Pi in the first place given its ridiculously low cost.
I think the appeal here is to add GPIO directly to a PC simply because having one computer is simpler than having two, and there are a lot of cases where you'd like to just toggle a pin here and there without having a middleman machine.
I think the appeal here is to add GPIO directly to a PC simply because having one computer is simpler than having two, and there are a lot of cases where you'd like to just toggle a pin here and there without having a middleman machine.