Hamilton is desperate, he's fighting for a championship which he is currently losing. McLaren are the third fastest car at the moment, and they aren't going to win the championship by coming third.
Out of the 2 drivers Webber was the bigger idiot, he has potentially the fastest car and the championship lead, he shouldn't have taken such a big risk and resisted the move so hard, it just wasn't worth it. Finishing 4th behind Lewis would still have left him in the lead of the championship, at a track where he was at a disadvantage. In the end he was probably the luckiest man this season! as somehow he finished the race which the tyre nearly off the rim.
Here's something to ponder. If Hamilton had gone wide on the exit of that corner to give Webber room he would have had to drive wide over that curb in to the run off, riding the curb would have given room but compromised exit speed and possibly damaged the car. Drivers have been penalised for doing such a thing. Bearing this in mind when Lewis arrived at the corner ahead of Mark, potentially he was damned if he did and damned if he didn't.
“If you no longer go for a gap that exists, you are no longer a racing driver.”
—Ayrton Senna