We have developed a mobile game and obviously most our textures/images are compressed. Now we're considering to release the same game for PC and Mac as well, but would like to disable all compression to get the most out of the graphics.

Would you say it's hard to add such a feature for the "Publish Project" dialog?
Simplify Materials is not the same. A setting like "Image Compression" would be good, having options like "Disable", "As Defined".