Why not offer 2 versions for download and let the user choose, whether they want to block their whole disk with a single game, or accept a bit longer loading times? Or let the user at installation time make an informed decision by explaining the supposed optimization? Or let the user decide before downloading, what resolution (ergo textures) they want as the highest resolution they will play the game at and only download the textures they need up to that resolution?

Questions, questions, questions.