The Thin Red Line DVD has the Melanesian Choir soundtrack on it.

The original DVD release of The Mummy [1999] had the soundtrack as an Easter Egg on one of the menus.

How come more DVDs don't offer the film's soundtrack or score as a bonus feature?

I think this'd be a great feature.

I wish more DVDs had this feature too. I love the isolated score with The Matrix.

This would have been a great feature on the upcoming Cruising DVD.
The soundtrack is OOP.
I have it on vinyl but would love to have a CD of it.
It would also have been great if it included the instrumental music by Tom Browne & Barre Phillips whick is not on the soundtrack album.

I don't have all the details memorized, but I think there have been protests from the musicians' union that the performances used in the film can't be broken out from the movie -- it then becomes a substitute /competition for the soundtrack album/CD, which is covered under a separate contract (even if there is no soundtrack album/CD). Whether this is a clear-cut contract issue or not, I don't know. There have been some recent releases that have this feature (can't remember the most recent older title that had this) so it isn't dead, but it used to be more common than now.

Pee wee's big adventure has an awesome isolated score track with commentary from Danny Elfman.

Yeah, it's pretty ridiculous it doesn't happen more in region 1 land. There are a ton of releases from Korea and Japan that come with the OST and it's a feature that I would prefer over any other extras (well, considering most aren't English friendly anyway). Though none of these exports are Hollywood films. So there's probably a point behind the musician's union obscure brought up.

It's probably just not a popular feature, all things considered.

on the top of my head:

John Carpenter's The THING (old release) ---- isolated score
Dario Argento's SUSPIRIA Limited Edition DVD ---- separatae CD
Daro Argento's OPERA Limited Edition DVD ---- separate CD

Superman the movie(older release)------isolated score
Jane Eyre (1944)------score and sound effects.
Halloween II (old release)--------isolated score

There are a few more for now.

Money.

Why sell one when you can sell two. Honestly I can't blame them either.

At the very least I would like a track listing. For a show like Scrubs it would be perfect because they play alot of decent songs during the show & it would be nice to know the name of them all.
I'd rather have the film/TV show's soundtrack/score than another one of those boring "Making of" bonus features. I'd also like more "Bloopers" on DVDs as a bonus feature.

The standard reason I heard from a few years ago was that the isolated soundtracks were being pirated.

Cine Paradiso 4 disc Deluxe Edition Region 0 (or was it 2) includes the grand Ennio Morricone score CD. I think this a great bonus for any DVD release.

Ocean's 12 score way way cool that I bought the OST CD!

Yea I heard that too but I think it's kinda silly for a reason. I mean, it's easier to rip a CD than a DVD right? Unless, of course, if availability of the CD is not a problem.

I remember when the LOTR:FOTR EE was first announced, an isolated music track was listed as one of the tentative features. It was dropped because of space issues, along with an effects-only track.
http://www.thedigitalbits.com/mytwocentsa62.html

I'm thinking that a lot of DVDs don't contain the isolated score because it's an extra feature with low demand. I believe that it's sometimes an answer on those "what special feature do you like best?" polls studios do, and I doubt that most people select isolated score over more standard features like making-ofs or commentary tracks.

Current R1 Collector's set has it.

How about soundtracks that were never previously released? Holy Mountain on the Jodorowsky box set.

Sounds reasonable to me.

To date probably my favorite extra on any DVD.

If I remember this correctly, The Sweet Hereafter has the score embedded in the menus. You basically just leave the DVD on the main menu, and it chooses random selections, I think.

That happens all the time. They are ripped verbatim (edits, volume drop-outs and all) and placed on CDs, sold as "complete scores".

I do that for my own personal enjoyment. I also go the extra step and edit the music to compensate for the volume changes and revisions, completely customizing them and no one else will ever have one like it. I even include the original album CD tracks, and edit those to include the additional material if needed. So I beat the bootlegs out there. I do it mainly because it's just a fun process to me. I've bought the DVDs and CDs for them and have NO desire to make money off my customized versions.

The original Apollo 13 Collectors Edition from 1998 has the "For Your Consideration" Oscar promo album in its main menu.

Legends Of The Fall and Jumanji special Editions have isolated scores.
The Region 2 Glory and Bicentennial Man DVDs have them as well.

I recalled a dvd had the score playing during the menu, and if you let the dvd sit, the entire soundtrack would play. All I could remember was that I own the dvd. I was trying to remember which one it was. Thanks for refreshing my memory.

The new Tyrone Power boxset has an isolated score for the superb Captain from Castille (1947).