Right now players can only select from a few post-processing presets, however, many players don't like the motion blur that results in selecting any setting higher than very low, and some players may also dislike bloom. Right now there's no way to have a configuration like-

HBAO On
Bloom On
Motion Blur Off

For one example. Or even a setting where the only effect enabled is the game's bloom. More flexibility and control over these settings gives a better user experience by allowing users to have the specific effects they like, or to turn some effects off to save performance while still keeping others.