I love soundtracks and have a bunch.
As commercial releases, they tend to be recorded to a higher standard than run-of-the-mill music albums or CD's are.
It could be that the more recent ones are recorded at 24/192 for DVD/video....and downmixed to 16/44.1 for CD. But, even the vinyl versions of most sound tracks sound better than commercial counterparts....and that goes back to before they recorded them digitally.
I love Gladiator, Star Wars, O Brother, Where Art Thou?, Red Violin, Good Morning Vietnam and so many others - too long to list!
John