I don't buy the weight limitations being the issue with demand - look at ANY factory roof rack and they all have limits under 200#. Automakers don't want the liability of you taking an already top-heavy vehicle and throwing 500# on the roof and having it tip over around a slight bend.
I think it's exactly to do with the fact that they P38s just aren't widely used for offroading or expeditions. No one is going to go to the effort of making serious parts without market demand being there. Hell, my lift is cobbled together from OME springs for the Disco front and Defender rear. My personal opinion on P38 vs D2 - those of us who enjoy attempting to traverse the state/country/globe in the world's most unreliable vehicles are a quirky bunch, and I think the unique/quirky styling of the Disco, the Disco's larger rear cargo area, and the daunting electronics of the P38 combine to make it a rare offroading platform. Then you have the chicken/egg scenario where the existing aftermarket support sways more people who were neutral to them both towards the D2 due to aftermarket support.
All that to say - LET'S CHANGE THAT, ONE PART AT A TIME! :sombrero:
It's an awesome platform when it's beefed up and I've been enjoying the hell out of mine. So, who wants an expedition/safari/overlanding/glamping rack for their P38?!?!