There are benefits to long-term momentum-building marketing. Warner Bros. pioneered such marketing in 1989 with the first Batman film. The result was "batmania," a pre-film hype frenzy that translated into a) the film being a huge box office success and b) some $750 million dollars worth of merchandise being sold prior to the film's release. As such, the marketing payed off in spades. It was costly, but the benefits were well worth the cost.
Other studios began employing the long-term marketing strategy after that. With the release of Batman and Robin, however, WB ran their once-popular franchise into the ground. They didn't risk a large scale marketing campaign for Batman Begins, and while Begins was a success in theatres, it was not as huge as it could have been. With The Dark Knight, however, WB presented a huge 1989-reminiscent marketing campaign that put TDK in the news continually and made the sequel as smash hit. After the tremendous success of TDK all WB had to do to market TDKR was use a relatively tame marketing campaign.
The problem with MOS is that they are employing that TDKR style marketing campaign (actually even less than that, as cragdbfan noted), hoping that Nolan's name will draw in audiences, rather than employing the more successful campaigns that they are better known for. The risk, however, is that MOS may only have a mediocre presence in theatres if things don't pick up. There is also the further potential loss to merchandising sales that would otherwise be higher with a batmania-esque hype.
Yes, there are costs and risks to all marketing strategies. Here, I'm critiquing WB's current strategy as following a faulty paradigm (the TDKR paradigm) when they should be putting more effort into things. It doesn't have to be the level of Batman '89 and TDK, but it should be more intensive than it is right now.
