The limit on total number of traits in the vanilla game really annoys me; with only four traits to choose from, I always end up with unspent points or only three picks total; I wish there was a way to take 5+ traits as long as the total of the bonuses and maluses even out to 2.

And yes, I realize that I can just voluntarily limit which ones I pick, but I think that this would also fix the problems people are reporting with AI races taking absurd bonuses; you wouldn't need to work out any way to make the AI play by different rules from the player, because they couldn't make themselves overpowered anyway.