Professionally trained soldiers alright, standing behind their target, isn't laser supposed to be strong enough to penetrate? Though it never really has in any movies etc.
Stormtroopers are always doing stupid shit, but hey it looked cool in the movies, they also probably didn't expect getting their arses kicked by a blind guy armed with a stick.
But they aren't actually "lasers" all the guns that fire those "laser" looking projectiles are called Blasters. As far as I remember reading, they fire bolts of energized gas, so like plasma or something, they explode on impact with varying degrees of damage. I know it's something along those lines anyway, I am sure there are more nerdy words out there for it.
And on Rogue One, it is one of the best Star Wars movies made, I don't care what anyone says, it's an awesome movie overall and it had the most epic fucking ending. I watched it twice at the Cinema, once with a friend so I could enjoy it myself and judge if I think my Son would actually watch it all, then again with my Son who is a Star Wars fan and yes he did enjoy it, he almost shat his pants in excitement at the ending when Vader fucks shit up.