I'm not a technical bod myself but I thought the way they originally filmed this best sci-fi drama ever to come to TV meant it couldn't be converted to blu ray?
I’m not speaking specifically for B5 but the biggest problem is that in the mid-80s TV started to change from filming in traditional film, to video tape. Film as a media can store far in excess of 4k, so by switching to video the native resolution was as low as 480p.
At the same time where special effects were needed they started to be done on computer. But due to limitations and cost in the technology at the time, graphics were rendered in SD.
So even if content was filmed on film stock, the film was scanned into video, and all post production including effects were done on video, and transmitted in SD resolution.
So even if you can go back to the original film to produce HD or 4K remasters, any effects or post production was only done in SD, and particular for Special Effects , up scaling from SD to HD and especially UHD just doesn’t cut it.
So in the case of Star Trek TOS and TNG they actually were shot on film, so they went back remastered the content for Blu-ray and HD broadcast, and actually recreated the special effects in HD from scratch, which was tremendously expensive.
but for DS9 and Voyager there doesn’t appear to be the economical business case to redo the effects like TOS and TNG. Enterprise though was finished in HD which is why we got the Blu-ray.
B5 is not as popular commercially as Star Trek, was shot on film, but I think it’s a very huge leap to get to justifying using the same techniques to generate HD or UHD remasters.
Of course for other shows that were only shot on video initially, there is little hope for remastering fir HD or UHD.
That said, there is always the hope that leaps in computing power and AI techniques will produce very good upscaling. But it’s still expensive to do at the level of computing power used to upscale some of the movie content. Time will tell.