Yeah, it's a good theory, but not airtight. For example Leia takes out a Scout by slamming a stick (not piercing, but sideways) into his (armored) chest. If the Trooper armor is designed to resist blaster bolts, it seems to have done a poor job, since we never see them get back up again after being blasted.
Then again, perhaps you could argue it's one of those things where it just might save the guy's life rather than him just shrugging it off like nothing (like a modern day bullet proof vest.. it might still take you out of the fight, but you could recover without the wound being fatal). That would contradict the common rationalization that the Empire "doesn't care about it's soldiers" and this is why they don't put shields, hyperdrives or missiles on their fighters (though this too is an assumption, mostly based on game mechanics rather than the movies themselves).
Some have pointed out that the holes blown in troopers by blaster shots in the movies are smaller than the holes blown in walls by the same blasters. Nice, but of course it just goes to show that the armor is not quite effective with dealing with the weaponry they're going to be facing in combat. If it was so great, why don't the Rebels wear it too? (appart from the obvious "bad guys are faceless drones in scary suits" cliche of sci-fi/fantasy).
I guess you have to argue that she's unwittingly using Force enhanced strength in that case or something... (and/or that Scout Trooper's armor sucks worse than regular stormtrooper armor).
It should also be pointed out that although the Clones appear to be able to see through the dust and smoke when fighting droids on Geonosis (AOTC), they seem foiled well enough by R2D2's "smokescreen" in ESB.
Ah yes, Curtis Saxton's "Endor Holocaust" scenario.