"In all fairness it is a valid question to pose.
Genetically altering humans is a fairly big ethical question. Granted curing color blindness is fairly harmless, but once we know how to do that and accept it can be done it pretty much stands to reason that we will find out how to do other things and will accept doing those."
True, once we learn how to genetically alter humans, we will be faced with the question of what alterations are ethical, moral, acceptable... However, the fact that a technique raises questions does not make a specific use, in and of itself, unethical, immoral, unacceptable. Consider the concept that we should not create explosives because they could be used to harm people. That is true, but explosives can also be used to facilitate mining, construction, etc. There is no doubt, for instance, that Alfred Nobel's invention has been a boon to mankind (even though some have abused it). There are [more expensive] alternatives to explosives. But many of the issues that gene-therapy could resolve have no good alternative cures (there may be the means of treating the symptoms, but no cures). Should we deny the cure on the fear that someone else may abuse the technique?
When I was in grade school, I frequently encountered teachers who, rather than try and determine which two or three students were talking in class, would simply give the entire class detention. Rather than deal with the specific case of abuse, they took the easy way out and penalized everyone. Banning gene-therapy on the fear that someone might abuse it is wrong. It unfairly penalizes those who have done nothing wrong but might well benefit from it.