All the top drivers have suffered DNFs:
Hamilton (DNF when he was in 2nd place, penultimate lap)
Vettel - multiple DNFs
Alonso (DNF when running in a safe 2nd (was it?))
Button (DNF Monaco)
If anyone can feel hard done by, it has to be Vettel, but the remaining drivers have all had equal DNFs. Webber has been the lucky one, but I'm confident over the course of the season, it will all even out.
As long as we continue having dry races with generic strategies, you will continue to see Hamilton outperform Button. This simply down to his basic speed advantage. This is evident where both Button's wins have come in damp/wet (non-generic) conditions.
The minute we start getting topsy turvy races, especially in the wet, Button should be able to gain an advantage over Hamilton.
If Hamilton can learn to make his own strategic decisions and get them right, then he shall definitely be set fair to attack MS's records, but until then it is going to be tough, especially when you consider that Alonso is still a young man and at/near the top of the game.