To be fair, leitmotivs are the main reason, I do think. They are an easy go for remixes, and they scare remixers a lot less.
That's mainly why retro tunes are now one of the rules, because they heavily relay on leitmotivs to deliver, when more recent OST is more free due to less contraints.
Added my vote, I may sound a bit mean sometimes, but I promise you I'm not, I try to be as constructive and relevant as possible.
Nice round, and props to everyone that submitted an entry !