I believe that being too commercial isn't such a bad thing because, especially for a new game/developer, getting the right recognition and advertisement can make the most unfamiliar or obscure game the next great series.
What I don't like is when they advertise to those people who are not intentionally the target audience. Dead Space 2 did this by making a marketing campaign to sell games to teens by showing the reactions of mothers/women of different ages to the game's gory gameplay. Yes, we know, everyone as young as 8 is probably playing Black Ops even as we read, but there is no need to be so blunt like this marketing campaign.
It sets up a bad image that the developers want your money, no matter from who or where. In this case, the developers will become more lax with their game development and either release a game that is blander than the previous installment or a new installment that has too many bugs to work out (and are never completely resolved).