They release iasw merch every now and then and it's often such utter crap - like the iasw "inspired" art work by someone named last year. (or maybe two years ago?) Why the eff (sorry) do they need iasw art from someone named ? Mary Blair not good enough???
Anyway, there are exceptions... the Christmas ornaments from a few years back were great... and in Disneyland at some point I was able to order prints of some of Mary Blair's concept art for the ride.
But, yes, in general there should be more iasw stuff.. it's just the stuff they produce is never the stuff it should be.