Actually this is one of the better balanced traits. It allows you to get out a number of cheap settlers and set up a decent empire, without crippling your growth, and then later you can use that empire to attack someone else and get great generals to improve your military might, and production of military units.
What it is weak for is "pure agression" players that, as stated somewhere else, build two cities and send a rush to take the rest of their empire from somebody else.
It also has great synergy with the Great Wall. So you throw up your first four or five cities, build the great wall to keep the barbarians out, and when your victim tries to counter attack your defenders get another 100% bonus to cranking out those generals.
I think the trait is under valued mostly because a lot of people either play total war, or total peace. For a balanced, non rush, strategy the trait is actually fairly powerful.