You do realize that it takes all of 2 seconds to shoot 6 rounds, right? This entire event lasted less than a minute.
It's not like Wilson shot Brown once and said, "Hmmm, I wonder if that will stop him?"
They are trained to shoot until the threat STOPS.
This isn't TV or a movie or some cartoon fantasy-land.
It's easy to sit at a computer and say, "Oh, I would have done____!" or "I wouldn't have done____!"
Until one's life is in danger, after being smashed in the face by a giant and him trying to steal your weapon, I don't think someone sitting on a comfy chair/couch on a computer can pretend to be in Officer Wilson's shoes.