This is a side effect of all characters having the same point-buy amount and to a lesser extent the removal of fixed racial attribute scores. Characters like Minsc and Halsin should have really high strength based on how they look (and based on Minsc's stats in previous games) but their classes don't really get much benefit from high STR so unless you give them an increased point-buy amount it would just be gimping them. With how you can respec any character to be any class as well, there's just not alot of reason to use most of the later non-origin companions.
This is only the case after you recruit them, while they are still; npcs that you can fight, they have inflated nearly all 18 stats.
People say that the dice are loaded / game is rigged? Thatss due to the inflated stats a lot of the enemies get in combat. Your DCs will never be a match for enemy stats.
