Brown happened to fit the description when he was out on the street, You would be a fool not to stop and question him.
I don't have any beef with how the police officer wanted to question him. However, he didn't 'rob the store'. He shoplifted, which is a much less severe offense.
Nobody is complaining about why Mike Brown was questioned. It's the fact that he was shot and killed even though he was completely unarmed and surrendering (according to witnesses).