I don't think anyone who knows the genus Dimerandra considers it 'less desirable' than other orchids, but it is definitely less popular than many others, and there are reasons for that. At some point most hobby orchid growers with more than a few plants begin to specialize in one genus or alliance or subtribe, or a few. Dimerandra is a small genus with only one species at all common in cultivation, with a narrow range of colors and forms. Technically in the Cattleya alliance but with no hybrids... If you've seen one Dimerandra you've pretty much seen them all, so they don't inspire collectors like the big diverse groups. It isn't exactly rare, and it can be gorgeous when well grown, but there is just no reason to have a whole greenhouse full of Dimerandra. And it isn't difficult to grow, so it doesn't need long detailed cultural information. I guess that adds up to what seems to be a limited amount of information out there. You might find some older sources that list it as Epidendrum or even Oncidium, but I don't think those will add much to the total.