I wouldn't say that this is a particularly weak class for MVPs compared to recent years. Nash, Nash, and Nowitzki won the award from 2005-2007 and I would say that was a much weaker class than this season.
Rose benefits a lot because he is one of the only players to play on an extremely good team with lack of help from a second star player (it's more than fair to say Boozer is not a star player anymore).
Durant has Westbrook.
Bryant has Gasol.
James has Wade (or vice versa, depending on which way you want to look at it) and Bosh.
Ginobili has Parker (and some serious depth)
Rondo has KG. KG has Pierce. Pierce has Rondo. And that entire team has some serious depth.
Howard, like Rose, lacks a second star. And I don't blame someone too much who thinks he's the MVP right now. The Magic do have some quality starters though (Nelson and Richardson) and some more depth beyond that (Tukoglu, Redick, Bass, Clark, Anderson, Arenas, Q-Rich).
Nowitzki doesn't have a second star either. And the Mavs actually have a little better record than the Bulls. But Terry, Kidd, Marion, and a much-improved Tyson Chandler are all not far away from being All-Star caliber players. Rose has 3 other guys who could potentially be All-Stars. And Butler was there for about 30 games. That did help the Mavs rack up some wins early in the season. And the Mavs had a stretch where they dropped some games because Nowitzki was hurt. So that hurts Dirk in that regard, too.