Yeah, I was just as impressed with the new music in the sequels as the remixes. The Marine Tube theme still never fails to blow me away, even after all this time. Oh, I don't like Barry's Theme all that much myself, much prefer other tracks like the Frontier Brain battle theme, Dialga/Palkia battle theme, Giratina's battle theme... Sinnoh had some brilliant location themes as well, Eterna City is the one I always spend the most time in, just to listen to the music on an endless loop. Sapphire was my first game, so I have a lot of emotional attachments going on with the music. Also feel obligated to post this, in case you haven't heard it. And if you haven't, then you need to.
It stands to a point that Theatrhythm, while being also a treasure trove of brilliant FF music, is also stupidly fun to play. I'd really recommend it, if ever you have the time.
Yes, the fact that such a long-standing series, with numerous installments, each with their own soundtracks which vary so much internally anyway - produces such good music in such quantity is really quite amazing. I find myself discovering new music in the series every day, and only recently I've been caught up in listening to the OST of the HD remake of X, which is incredibly interesting. Close to every single track has been rearranged/remixed, and it's fascinating to hear new interpretations of familiar tracks. Some tracks like Besaid Island and Thunder Plains do feel like a step down from the originals, but I'm loving how they "rocked-up" the random encounter battle theme with the guitars. Makes it a whole lot more bearable, imo.