Uh, because if you have a pool of extra attribute points you can assign anyway, it makes no difference what the initial values were.
It would've made sense in a system like NWN2's, I guess, where the farther you increased an attribute from the base value the more points it cost. But then, it would have simply meant that a male fighter would be stronger than a female one, and a female sorcerer better than a male one. Which would've been rather pointless ultimately.
Given that attribute points are limited for the sake of game balance only, I don't really see anything wrong with a player character female being as strong as a male, so long as this isn't typically the case in the game world. Like AoD does it, that is.