Absolutely. Trevor Morris is a great composer. It seems Dragon Age likes to let a single composer do their entire score so it has a distinct style but Mass Effect uses several. I'm curious to know if that track in the recent trailer was his score. It sounds like his style of music and I thought the song was absolutely perfect for the trailer.
I asked him on Twitter but not surprisingly, he didn't respond. I guess they can't confirm that yet. 
As for music in RPGs, I feel it's critical. One of the few genres where music absolutely must be amazing...especially one that tells emotional stories. Mass Effect tracks stick out in my mind. When I remember most dramatic moments, I can remember the exact songs playing in those moments. I'm hoping to get that in DAI. Inon Zur was a good composer but I seldom remember moments like this in the first 2 DA games. Music can really help convey the emotion behind whatever mood they want.
I would argue it's even more critical in an RPG that involves so much exploration as it seems DAI will be partially aiming at.
Morrowind Theme
Still one of the most memorable exploration themes for me.