Actually, I was pleasantly surprised that FFV has some kickin' tunes.
Its kinda funny, though. At the beginning of the game, most of the soundtrack is orchestral, no real "modern" instruments, but as you progress thru the game, and meet Ex-death, you start hearing a lot of songs using Distortion Guitar in it, probably culminating in Gilgameshe's theme, which is the closest the OST seems to come to the Rock genre.