I always found Minsc to be weaker in BG2 than BG1, due to every other fighter type there having some kind of useful kit (or special abilities/absurd stats) and Strength simply not being that important anymore due to items and spells buffing that stat.
But even in BG1, his big advantage is having a high score in the physical stat you find the most (and best) potions for, while his other stats only give minor bonuses. And this isn't all that great, honestly.
Also, I'm pretty sure Minsc can't actually use scrolls due to low Int.
True, in BG 2, unfinished business raising his str to 19 helps. Plus, awesomer Boo.