The main non-scifi TV shows I care about which are not out/only partially out on DVD are:
L.A. Law - this was a HUGELY popular show in the 80's. Don't know what the hold up is with a DVD release. 3 years ago at the Vegas Trek Con in August, Corbin Bernsen said that L.A. Law would begin release the following October. And here we are, 3.5 years later, and still no L.A. Law.
Falcon Crest - Love this show, which lasted 9 seasons back in the 80's into the early 90's. Have no idea why this one hasn't been released either.
Cold Case - of all the Bruckheimer TV efforts, this is by far my favorite. I know that music rights must be the hold up here - all of that period-specific popular music they use for the episodes will be nearly impossible to get rights to. I mean, good luck with getting rights for the music of Bruce Springsteen, for example. They aired one episode that included ONLY Springsteen music.
Without a Trace - They have only released two seasons of this in the US...and no new seasons have come out in a couple of years. I'm coming close to ordering these from Amazon.uk, where you can get about 3 more seasons, at this point.
Hill Street Blues - only two seasons have been released, and this was a bloomin' LANDMARK series which changed the face of TV. WTF?
Cagney & Lacey - only the first season has been released. And that was about a year ago.