It's a matter of social conditioning. In the CG community we are generally conditioned to regard Rosewood as superior and more valuable. Also, mahagony generally doesn't look as dramatic or attractive as say IRW subjectively speaking. This along with a tonne of other unreasonable biases and prejudices exist within the CG community.
As far as tonewoods are concerned, it's important to reiterate that it is the quality of the wood and the skill/design of the luthier that matters more than the species itself, though the species does make a difference. With that said, I once owned a Cordoba C9 with solid Mahagony back and sides and I preferred it over many rosewood guitars that I have played, which included several "high end" guitars. This is not to suggest that it was the mahagony that made it superior. I'm convinced that any high quality piece of back/side wood can make a great sounding guitar when all the other pieces come well together. I sometimes even wonder if we can make a great sounding guitar using carbon fiber or "paper" for the back and sides as long as it is paired with good quality top and a skilled luthier.
In the end however, value will still continue to be based not on actual performance, but on the general consensus of the community.
"Success grants its rewards to a few, but is the dream of the multitudes.
Excellence is available to all, but is accepted only by a few." - Christopher Parkening