Cybernetic technology is fairly advanced across the Commonwealth, though how common and extensive the adoption varies between species. Some avoid all but the most necessary prosthetics, others embrace the technology as just another useful device, some even flaunt their merger with machines and see it as the highest form of advanced life.
The proliferation of aliens was a blow to humanity's ego, the human form and mind was no longer a uniquely valuable treasure in the universe. The sudden influx of new forms and ideas created a backlash. Human culture leaned toward idealization of the human form, so anything that deviated from the natural human form (deformity, modification, even too much integration into alien cultures) became seen as shameful or less than human. Cybernetics were still tolerated if they mimicked the original human organs, but heavy modification was only embraced by career military. This went into high gear during the Retribution War when the heavily modified Aethan Haht Garuud ground troops devastated conventional troops.
Full conversion heavy borgs were almost as terrifying to the civilians as the Garuud troops were, and the combat drugs that they were issued only further stripped away their remaining humanity. After the war, heavy borgs were seen as constant reminders of humanity's defeat, the sins of their government, and that aliens were a threat to the entire species. A number of high-profile incidents of traumatized veteran soldiers, now addicted to combat drugs, slaughtering innocents over little to no provocation, cemented humanity's poor opinion of cyborgs and cybernetics in general. Anyone with obvious prosthetics, even benign ones, is regarded with suspicion, fear, even outright hostility.