Of course we consider legislation. Who will be legislating? People with privilege. Are they likely to deny themselves advantages, or will they find a rationale for allowing people to buy enhancements? Already markets exist for buying organs in some parts of the world, and proposals for this practice have been put forth in the US (and other countries).
Interesting post, @samminator. With my background in humanities I bring perhaps a different perspective. You speak of colonialism, of the possibility that machines will colonize humans. I think of something even more imaginable...enhanced humans dominating those who are not enhanced. The privileged, who can afford enhancement, subjugating the lower classes who cannot afford this. The technology already exists for people to "enhance" their offspring, to choose the kind of child they want to have in order to insure a superior outcome. How far from that practice is the one of technical enhancement? It is the logical next step. A very provocative and important blog. Thank you, @samminator.