For anyone interested, I looked deeper into the Step By Step situation. In the previous DVD season set releases, Warners made several major screwups:
Season 1 & 2: ok but not ideal. The 4x3 content was encoded as 16x9 which means the black bars were encoded in the stream. 4x3 TV on DVD releases typically aren't done this way because it means that DVD's already limited resolution now is partially taken up encoding the black bars instead of devoting everything to the 4x3 picture. But at least the picture is not cropped and displays correctly.
Season 3: Flawed. The entire season was seemingly cropped, losing approx. 20% actual picture information. It's like they took an already-zoomed-in 16x9 master and then tried to master for 4x3 from that, which I'll bet is more or less exactly what they did.
Season 4: Correctly done. 4x3 encoded as 4x3.
Season 5: Flawed. Botched just like Season 3.
Seasons 6&7: Unknown.
Hopefully the new Complete Series set fixes these problems.
By the way, this show COULD be released on Blu-ray. It was shot on film and there are HD versions of it on some streaming services. I suspect the reason its not on Blu-ray is simply a demand issue.