Hell, I remember Lukas grousing "what the hell happened to movie posters?" in FSM...way back in 1996.
Posters truly are terrible these days, but the whole manner of how films are promoted has changed so radically over the last fifteen years, I can see why...it used to be, the only way you'd know a certain movie was coming out was to see the poster on the wall of your local theater a few months in advance. Nowadays, every tiny element of the film is pre-digested online for up to a year in advance if not more, so by the time a poster hits the wall of your local multiplex, anyone who wants to see the movie is well-aware that it's coming, right down to the specific release date, so why spend more money than you need to? I hate modern posters, but it's not gonna change anytime soon.
That video sums it up well, though I was thinking in regards to Frank Darabont who outed criticism; his movie "The Mist" has a poster artist in the lead, you even see him working on one, but I felt the posters for "The Mist" itself were awfully trivial and bland:
Come to think of it The Green Mile was not that special either, Shawshank Redemption was ok though.