F1 cars have amazing handling and braking. The lower speed corner and steady trajectory of Vettel was such that there was no real danger of anyone hitting him. It was easy for Hamilton to avoid a collision. So there was no significant danger created by the way he rejoined the track. There was also no reasonable expectation of Vettel being able to rejoin the track differently than he did. So to those saying it was a correct penalty... how? In what way is this a penalty?
If looking back at other instances of rejoining the track in F1 races of recent years, the penalty looks especially ridiculous. Drivers do far worse cutting chicanes all the time without getting penalties.
Did Vettel make a mistake? Yes obviously. Those saying that a mistake equals a deserved penalty... then why not penalize every other mistake drivers make? Does Vettel let his emotions cause him significant problems? Yes but that has nothing to do with whether or not it was right to change the result of a race.
Anyone who hasn't driven a race car and has no idea what it's like to control a car in that situation... why are you assuming that Vettel could have rejoined differently when you don't have a clue what it's like to drive a race car through the grass of a chicane? F1 drivers Brundle and Button are both saying there's nothing he could have done. It's silly arrogance to think you know better than them.
It's frustrating to see, after such an noncompetitive start of the season, to finally have a good battle for victory determined like this. I'm getting significantly less interested in watching this season.