What could be really exciting, is that we could develop a way to see other colors. Butterflies see many more colors than Humans and there are rare cases of humans with an extra cone receptor.
Maybe I'm just being sensitive but it's almost like someone was discussing a way to regrow a missing limb and you've come along to tell us you've always fancied a third hand.
I don't think one negates the other.
Are you sure that colour blindness would still present an issue? I've heard that in recent years the requirements had been relaxed around this.
I _think_ the key point is, as you said, that the different gene copies need to have different response ranges, or you end up functionally trichromatic even though the pigments are from different places.