The business sense of CBS Home video is ST:ENT has already been for rental & sale on iTunes in low-bit rate HD and streaming in HD. There is a limited realistic window of the life expectancy of the Blu-ray physical format for releasing film and TV shows before downloaded content purchases become mainstream and overtake Blu-ray sales and the quality rises to be close enough.
By starting to release them now they are getting in while the getting's good. DS9 & VOY may get a HD remaster for syndication and download but maybe not before Blu-ray sales as a medium are vastly declined already. I appreciate the additional special features as added content on the disc that Blu-ray offers.
I have always said ENT would be on Blu-ray before the 2nd new film.