I usually minmax since I like to play on the higher difficulty settings. But even from a RP standpoint, it doesn't make sense to me that my Assassin is not good at killing things. Therefore RPwise he SHOULD be good at killing things.
Same for any other role in the game. Why would a Wizard be bad at casting spells? Why would a Fighter be bad at fighting?
A couple of answers to what you wrote. First, not every assassin is Artemis Entreri (ie: an unparalleled master of martial combat.) Some are just good at sneaking into places, ambushing a target and escaping unnoticed. Assassins don't typically engage their marks in duels, they just kill them when they least expect it. What I'm getting at is that just because a character may be an excellent assassin, that doesn't necessarily mean they excel in melee combat.
To address your other queries: WWhy would a wizard be bad at casting spells or a fighter bad at fighting? Nobody says they would be. Just because you don't have 18 intelligence, doesn't make you bad wizard. The tendency of min/maxers however, as another poster said, is to have a wizard with very high intelligence with 6 wisdom. From a RP standpoint, that makes no sense but from an min/max standpoint, it makes perfect sense as they typically are only concerned with increasing their primary statistics at the expense of the others.
