First of all, what I'm speaking out against is the assertion that performed and recorded music is inherently superior to produced music. That is not the case, in fact it's often much worse.
Secondly, download (or use the sound test) an assortment of songs from melee. Listen to them. I just did that and not a single one was played by an orchestra. All of the leads were synthesized or used samples. Two of them MIGHT have had performed percussion, but I couldn't tell. That is the whole point, you can't tell and it doesn't matter. I get the feeling that you guys read too many IGN reviews or something, I can't imagine where you would get such a retarded idea in your head that music is inferior when not performed live. You can't even tell that melee wasn't performed so what does that say about your belief?
The reason melee's music was better than what we've heard of brawl is because the brawl recordings on smashbros.com are extremely muddy. They're mixed poorly and compressed heavily. Hell, on the ssbm official CDs, half the tracks were severely clipped. The arranged orchestra CD has misnotes all over the place, they just taped an audience performance. I don't have a lot of faith in their ability to produce quality audio.