Eh, there's more to it, the pathing has been one of maybe dozen components that came together like that.
There were more important factors, like having the limit to 12 units in a group - any more would make Zerg much more powerful - now Zerglings are easy to use en masse. Terran bio would benefit from it as well.
If the pathing of SC had been "great", the game mightn't have taken off the way it did competitively.