What are you, a completist? All the best seasons of "The Simpsons" are already on DVD (1-8), so it no longer bothers me how slowly they're released. "Dream On" deserved better than to have only 2 seasons come out, but I understand why the sales were too low for all 6 seasons to be out. It's obscure and forgotten by many. It's a shame, though, because it's one of the most consistently entertaining, smart, and creative shows I've seen and was incredibly consistent for 6 seasons (only a few stinkers scattered throughout).
I think releasing only a few seasons and then stopping before releasing the whole series is worse than not releasing any at all. Like I said, I understand the sales making execs reluctant to release more, but screwing over the consumers like that is terrible. I think once the first season has been released, they ought to follow through with the rest. It's terrible that WB released three volumes of "Animaniacs", then stopped with only one more volume needed for all of the episodes to be out on DVD.
I agree about "Batman". I wouldn't buy it (a little goes a long way, as it gets too annoying after awhile so I wouldn't want to watch all the episodes), but it is deservedly considered an iconic show and the best episodes are true classics in a completely unique way. I especially love The Riddler, Egghead, and Catwoman episodes. I think those are the best villains on the show and would love to watch their episodes in DVD quality.