The only argument I can make AGAINST fractional points is if someone is still pulling stats from the newspaper like I did in the old days.
Of course, if you're still doing that, I'd have to question the intelligence of your league in the first place.
The main argument you may hear is that it all evens out in the end anyway. You get some breaks, you lose some. However, you must counter with this argument:
If my 'bad break' comes in a game decided by less than a point, and my 'good breaks' come when I would have won by 20 points anyway, how is it really coming out even?
Fractional points is the only way to go.