Hey, plenty of Voidsent wear clothes. As a few examples, Echidna wears a halter, Feridad is pretty much fully clothed, and Succubi dress, as well! Sure, they're actually animated corpses, but I find it unlikely that the corpses they animated were all wearing succubus thongs, so evidently they dress themselves somehow. Even Cloud of Darkness has wispy rags covering her up a bit. No reason I can think of that high-ranking Voidsent can dress if and how they please, and Vampyrs would likely be near the top of the heap.
As for aetherytes...
They most likely DO exist, since the reflected worlds seem to be similar to the primary one - the question is whether or not they are still operational given the state of aether in a void-consumed world. In all likelihood, if we did go to the Thirteenth Reflection, they'd come up with some handwave that would allow us to use them; probably some gadget created by Cid that powers the aetherytes with the necessary juice transmitted from our world. Marketboards, though, probably not. Not that that's all that different from what we have already, with MB access only available in a few select places.
Possibly the most interesting thing about an idea like this is that the Ascians would be totally on board with it! Losing the Thirteenth Reflection was a major gaffe on their part, and if we found some way to salvage it they'd be all for it. It'd be interesting having them as allies, for a change.