That would be nice if they made mandatory for future games and made it available for as many past games that they could get it to work with.

While I don't have much use for it in singleplayer, I'd rather listen to something while I'm playing multiplayer.

I kind of agree with Supercat, in my eyes, Sony has less sway with 3rd party folks than MS and dare I say Nintendo.

Looks like custom soundtracks is an SDK feature that has some memory costs, which is why you probably won't see devs utilize it unless the game isn't as demanding (something like 12 megs or so).

Xbox has it abstracted out into the OS, so it doesn't cost anything for devs to use it.

Nope it's only very vocal minority that cares about it.
If someone can't live without it then buy Xbox and then you can even play FF XIII with your favourite Hip-hop ;)

It's a waste of power that could be used for the game instead.

No. The single player of most games has a great soundtrack, and in multiplayer you need to pay attention to the sounds around you.

I don't really care, I just want them to speed up in game XMB and friends lists etc...

Then how in the hell does KZ2 use it to perfection?  I mean,  if it's really that big of a deal breaker how does one of the most demanding games of the gen support it?   I think it's just not looked at as necessary by developers (or mandatory by Sony) and therefore a lot don't do it. 

I never saw the need of custom soundtracks, maybe in GTA is cool but in other games the music fits perfectly with the atmosphere for me, I wouldn't be able to choose a better one :P
Like in Oblivion the music is awesome! it will be ruined by "custom one"
and so on :P

I don't think many people will appreciate it.