>1/3 of the roster is useless
>the other 3rd is some gimmicky garbage that forces you to grind so much you would finish the game beforehand, and relies on hidden/missable

Pretty sure there the only missables are a few hidden items and chests. Also, I can't think of a single class that didn't have some ability endgame that felt really strong except maybe geomancer. Even classes that on their own don't shit out damage like beastmaster, red mage and ranger could be used to prop up other classes. FFV probably has one of the most cohesive class systems I've seen in jrpgs and when other games like Bravely Default try to ape the system, they overlook the cohesiveness that made ffv great. Literally every class makes another class better in some way.