It's funny that you said that because the thought did occur to me that there wasn't a movie adaptation. I can't recall if they did a comic adaptation of Trek 2009 (I think they did).
They did, and spun it out to six issues!
According to my friend who manages a comic shop, movie adaptation comics are no longer the guaranteed huge sellers that they once were. In the 80s and 90s, a comic adapting the script of a big budget SF or superhero movie, released within days of a movie's premiere, was almost a given. In more recent years, the publishers have found that tie-in prequels and sequels (singles or mini-series) to movies do much better, and can assist with the viral marketing program for the movie. It also lessens the chance of secrets getting spilled before the film's release, or the comic not matching up to last-minute editing of the movie by its director or the studio. Sometimes the publishers even use a movie's publicity campaign to re-release old, but otherwise unrelated, comic stories featuring the characters from the new movie.
While some fans delight in an adaptation showing differences with the mother product, others expect and demand screen-accuracy. Especially when the DVD is imminent and the fans have ready access to many repeat viewings.
IDW hadn't originally planned on adapting the 2009 movie. Sales of the "Countdown" and "Nero" mini-series were excellent, though, so demand warranted a film adaptation. Being much further down the track, the mini-series adaptation was able to incorporate all the dropped scenes (from the "bonus features" of the DVD) and even unfilmed, scripted bits, such as the proposed Shatner cameo (which he'd turned down). Had it been rushed to a simultaneous release with the movie, the adaptation may have only been a single issue, with hastily-drawn, often-inaccurate art, such as those early DC adaptations we got for ST III, IV and V.