Reflections, etc. are things that make up the good graphics, its not only about the polys.
This make no sense because if all that will be added to low graphics options it wont be low graphics anymore, it is option especially for people who have PCs that are incapable of running high graphics, thus it is made as minimal as possible in all aspects.
Besides all that, by going to advanced settings you can pretty much customise every graphical aspect you can think of, so again, pointless post.