It is great learning new moves. My favorite is the feeling you get when you finally learn the last of the four moves you need for the DSC (which in my case is always Sliding for some reason).

Then you can take four characters with DSC and one mage and kick the game's ass. I had so much fun schooling all of the final bosses over again in the post game with four fighters + Bleu combo.

I'd also like to point out that the SaGa series has incredible music. The Boss X battle music from SaGa Frontier can stand its ground right up there with the greats. Dreadful Battle from SaGa 2 and the Xagor Battle from SaGa 3 are good as well.