<snip>
The problem arises in that a pc with a mix of odd and even stats will almost surely place the +1s into odd stats (gaining an additional +2 to his total stat bonus) and his -1 into an even stat (losing nothing). THAT is the difference that I object to. I prefer the traditional +1, -1 scheme from 1e, but it simply doesn't work well with the current chart for ability bonuses, where every even stat is a significant increase but every odd stat is a meaningless decrease (or increase). To me, I find the breaking of that particular balance element highly distasteful.
I suspect that the thinking behind the +1 by race in 5e is that the +1 by class will do half the lifting. I'm of a mixed mind, but trying to remain open to the end results. We'll have to wait and see.
A -1 in an even stat costs a modifier. To gain the most, the player must put both +1 and -1 in all odd stats. The odd + 1 gains a modifier point, the odd -1 does not lose a modifier point.