“…the story really is of a primitive society–apparently a weak society–who is able to overcome a very technological society.” GL.
Asymmetric warfare is what Lucas is touching upon with the Ewoks vs Stormtroopers (and a powerful and pertinent lesson that is, as we’ve seen in the past decades with the West struggling to combat the Taliban and Al Quaeda), but the fact that they are the “best” troops is actually neither here nor there. You can remove the declaration that they are the “best” elite legion of Stormtroopers and the sequence still admirably achieves the intended goal.
Adding more firepower to the Rebel Strike team actually would water down that intention.