I saw this on a friend's Facebook wall, and it made me think, "Hmm..."
I really like the sentiment, but given how quickly human beings are causing the extinction of species (including the colorful ones) on a planetary scale, the basis of the opening position that human beings cherish "the variety of color in every species" is questionable.
It is true, though, that human beings DO like certain varieties of colorful species. To such an extent that we capture them, confine them, and forcibly breed them so that our personal enjoyment of them can continue. This is, after all, what zoos and aquariums do, and the basis upon which many historically rested their conservation platforms. Furthermore, this is why there is a pet trade (indeed, a "pet industry") that makes its money in breeding and selling animals.
The presence of zoos, aquariums, and the pet industry is a factually correct response to the answer to the first part of the "why" question that specifically responds to why and how human beings choose to provide conservation help to only specific species, even as human beings also continue to cause a planetary extinction. However, recognizing that we effectively treat the colorful animals that we love as virtual or effective slaves is a ... troubling response when considering the second half of the question.