While I partially agree, even from a gameplay experience, putting a 8 in a stat is voluntarily choosing a weakness, and a player should expect some kind of consequences from that.
There's level of "choosing" though. If you agree to rolling dice for stat generation, then you are voluntarily choosing the possibility of an 8. If the GM says the game is standard array, you take an 8 or you find another game. Only in point buy is it really all the player's direct choice to have it.