This might be about that particular build....
But I know from my own limited experience, the two weapon fighters need those extra attacks just to stay in the game. And they are penalized in various ways, including have relatively less punch when they move around.
For your charecter, he probably is looking to sneak attack...but he can't full attack off the surprise round, and he's got to get into position to flank, and may be a bit of glass cannon and has a hard time just standing there...but these things do depend.