A couple of nights ago I had a discussion with the group that is taking part in the C&C campaign I am running about some of the other game systems I prefer such as B/X and S&W. One of the comments that one of the players made was that B/X or S&W do not allow for the character concepts that he prefers. He stressed how important it was to him that the mechanics of the game allow for differentiation between characters. This is a view point that I don't share and I tried to make the counterpoint to him but I think that I was unable to persuade him.
I played a one-shot a couple of weeks ago in a game that was a mash up of Basic Fantasy Roleplaying and Swords & Wizardry. Attribute generation was basically the same as in B/X - 3d6 in order and some 2-for-1 swaps between attributes. The attribute array I rolled led me to make a thief. He had low hit points and not much starting gold. I quickly decided that Kilgor the Thief was a cowardly sort who would hide when he could and flee when he couldn't. He would avoid melee combat at all costs. Nearly every gp he had went into buying a crossbow - no armour and his only melee weapon was a dagger.
Kilgor the Thief didn't live long enough for me to come up with a reason why he was a coward but he was different than any other thief I have played. And it didn't take mechanics to make him different.