I thought that they balanced Thanos' personality quite well to make it work for a mainstream audience, whereas, in the comics, it might get a little bit too deep, philosophical and psychological to simplify and translate fully into this format.
In fact, I recently read Starlin's Infinity graphic novel trilogy, and the first in particular, Revelation, is terribly-overblown psychedelic, philosophical bollocks, and very disappointing compared to his comparatively reined-in series such as the classic Infinity Gauntlet.