Several tests are showing that rolling characters tend to be better than characters generated with point buy. Biggest back draw on point buy is that there is no chance for any natural 16 to 18. This point-buy system forces characters to be very stereotypical characters like a high elven wizard, dwarven warrior or cleric and so on.
A slight improvement would be this system which at least allows having natural 16s.:
Still, 27 points to distribute
14 6 (instead of 7)
15 7 (instead of 9)
16 9 (new value)
Yeah, you could have now three 16s but three 8s too.