Eugenics typically carries a negative reaction because it is most commonly used in fiction by governments to genetically engineer super-human soliders, the best examples I know of being the Space Marines in Warhammer 40k and Clan Warriors of Battletech.
http://en.wikipedia.org/wiki/Space_M...er_40%2C000%29
http://en.wikipedia.org/wiki/Clans_%...#Warrior_Caste

I'm a bit leery of allowing people to alter their own genome, because that's a really dangerous precedent to be set.

What it essentially will do is split the population between those who can afford such treatments and those who can't, essentially beginning every single "have and have-nots" scenario ever envisioned, screwing those who can't afford the treatments or those who are morally opposed to them. It will create a closed circuit of successful people, as those who are successful would be able to ensure their line's continued success by ensuring their children have the options to treatment WIDE open to them. This kind of thing is too socially impacting to be left to commercial disbursement, it would have to be government ran from a more Socialist government to be remotely fair.