Those pictures highlight so much of what is topsy turvy about the EU.
The sail barge in ROTJ looks that way because it's supposed to evoke our cinematic collective memory of maritime sailing ships from old pirate movies (sailing on a Dune Sea instead of a briny sea).
But now the sails and the railings are Hutt architectural styles.
It would be as easy to make the footage look like those concepts as it would to make the Endor footage look like a desert planet.