I mean, it does also illustrate how the empire's strength lies in numbers and resources, and not in superior skill. There's some evidence that stormtrooper accuracy is a lot better than popular media gives credit for (e.g. "these blast points are far too accurate for sand-people,") and the only reason stormtroopers miss as much as they do in the movies is because they are under Vader's orders not to injure Luke and Leia, which may or may not be true, but the battle on endor shows how susceptible the armor is to guerilla warfare that does, in fact, utilize those lower-tech weapons. I'm sure if the empire cared enough about the efficacy of the armor, they could develop a suit that incorporated shield technology and win battles with a fraction of the troops they use, but again, the suit's primary function is to mark these shock troops as the face of an insurmountably vast empire. I would not be surprised if the poor defensive qualities of the armor are intentional, to foster a strategic message to the empire's enemies that says "we don't care how many you kill, there will always be more."