I disagree, there are good subs for music and good subs for movies...
In an HT setup I want as much output as possible and tend to not care as much about the size of the enclosure. I don't care about a little port noise its just a movie, I know some people spend tons of money on HT systems but the truth of the matter is, you are watching a movie, get over it, your not doing "critical" listening, your not going to notice a little cabinet resonance or port noise, I have been on the sets of a few films during production and there is nothing controlled about how the movie is recorded, and I was on the set of Brotherhood for a bunch of episodes and I can promise you TV shows are even worse" you have cars driving by tons of ambient noise, I have watched movies and heard production talk in the background, so if you think you need $10,000 super clear speakers for HT you are wasting your time, get a sub that is not muddy and has enough output for your tastes, some nice flat mains that you can live with for long periods of time {soft tweeters and laid back is my preference} and save your money... Ported subs fit this bill...
Now with music.... You want fast tight bass, you don't need a lot of output {at least I don't}, a 300watt sub will keep up with a 200w set of mains with zero issues, I would rather have a smaller enclosure for music so I can fit two subs and they don't look silly next to a small set of bookshelfs, and I have a b tested comparable ported vs sealed subs and sealed has a more realistic/musical sound, sure there are ported subs that sound good with music, but get that same sub put it in a small sealed box and then compare it, if you think having the ported enclosure sounds better you are lying to yourself because you want a ported sub...
And I agree that a good speaker will be good for music and HT, BUT some people like forward bright speakers for their music, so it pops out at them, you put the same set of speakers in front of a tv and you want be able to sit through one episode of The Nanny with out a bottle of Advil... I have heard speakers that sound good with HT but I dont like them for music.
Me and 3db obviously have different tastes in equipment, for example your PSB image series, I could sit through a movie with them no issue but for music I wouldn't set them up if they were free. and the LV12r is also fine for movies, but I have now heard two different units {the one I bought my mother and another one Steve got for his basement HT} and I hear a mechanical noise in both, Steve and my brother also hear it but to them its not a big deal and with HT I agree but with music I would NEVER add that to a 2.1 system, there are much better sounding sealed subs...
So not to argue, we all have our different tastes, mine just happen to be the good ones

jk, lol... I prefer sealed for music and of course would also like sealed for ht but it would cost much more I would need 4 of them to get the "rumble" iget from a single ported sub...