CatBus said:

I think the previously stated reason was that the Blu-ray doesn't really have more than 720p in detail (even though it's 1080p, the film transfer isn't so great), so there's not much point in 1080p until some source better than the Blu-ray becomes available. Not that it couldn't be done--it's just a lot more time and a lot larger file sizes for something that, for the most part, won't be noticeably better even in the 100% BD-sourced scenes. Cue shot of Tarkin at 720p and 1080p...

Hmm, while it is true that the Star Wars OT blu-ray transfers are not the most detailed transfers out there, they could definately use a 4k remastering, they still look noticably better in 1080p than they do in 720p IMHO, at least from my experience encoding to both 1080p and 720p.

I am certain that his Despecialised releases would look better in 1080p and now that he has the processing power to handle it, why not?