I'm assuming the licensing for that would be pretty rough, even though it was in LBP, you'd be surprised how hard it is to get it on a new version or w/e if it wasn't done in house or by Sony themselves. Case in point - JP PSN vs. the world. That was one of my favorite themes/levels/worlds from the original LBP, and the song was just so damn catchy.
As others have said though, I agree that the main theme song from each respecting character/world should be used primarily - or at least something that's more striking.
A lot of the videos are from show floors so it's really hard to hear the music but some of the older gameplay is direct feed and you can hear the music - but it's still barely there. I agree the most recognizable themes were the Patapon theme and the Hot Shots Golf theme, all the rest are kind of dull and boring, most especially the Hades theme, I was really disappointed with that.
Why couldn't they use the theme you hear when you first enter Tartarus in GoW III, and have it build into one of the epic themes? This is the one I meant:
http://www.youtube.com/watch?v=EulHBvcbJnE
That could be the intro, have it slowly build into epicness. I just feel like what we've heard of the "remixed" or "arranged" Hades battle theme, it just sounds lame in comparison to the original:
http://www.youtube.com/watch?v=p_JtztEl4LE
I dunno, maybe we haven't been able to properly hear it, or maybe it's not a final version we're hearing, but it definitely doesn't compare. In SSBB, basically all of the arranged and remixed themes were amazing, as a Nintendo fan they floored me ... the redone versions in this have so far been pretty underwhelming.
One thing I worry about is how the levels are mash ups, cramming two themes together can easily make one or the other, or even both lose their impact.
One final thought - I always found the Hades fight/theme to be boring in GoWIII (in comparison to others), they should have done a mash up of the Poseidon theme/level, which is arguably the best set piece in the entire game (IMO):
http://www.youtube.com/watch?v=cY0QmzP2VZA
I mean, come on. That's just epic, classic GoW right there. The Hades theme is too brooding and not as impactful. I know, this would pose a problem for the Hydra mash up in the Metropolis stage (because both monsters are similar) but they could've easily put something else in there.
Imagine this - the stage takes place on Gaia while she's fighting the giant Poseidon monster thing, while ... I dunno, plasmid mutants (from Bioshock) fight the armies of Zeus all alongside Mt. Olympus. This could also have the fight move towards the lighthouse from the original Bioshock as they crash into it and fight around it. I think that would've been WAY MORE AWESOME than the Hades stage.
I agree the music in this game is a bit disappointing. I really wish that they used Poseidon instead of the hydra in R&C level.....
Games like dissidia and SSB had very impactful music, they also don't have to limit themselves to the characters feature in the game...playstation does have a lot of franchises you know.