Yeah, he was powerful and unique and cool, but he didn't have Phys pierce, which meant that the final boss was resistant to his attacks and it made him inneffective.
This was an issue they fixed with Raidou, and what they are now fixing for this version.
And yeah, you did use him, but he was in the Ass end of the Labarynth of Amala, so unless you saved a bunch of bonus bosses until the end of that thing, you had only a few bosses left in the game for him to be used against.
Not saying he wasn't awesome, but that just how it happened.
Now I wanna play the original with Dante hacked into the starting party with the same level curve as the protagonist, that would be fun. You'd get to use him the whole game at that point!