If everything in the universe were done to be practical/advantageous, then indeed it would be a dull and lackluster place IMO. There is a fascination for many with the Fluorite crystal. The very fact that it is a single crystal is intriguing for many...and therefore it becomes advantageous! I would want to have one...just because...which is plenty sufficient reason in itself, and at times this is more of a reason to do it than anything "practical".
This is the eyepiece forum and the technical aspects of the eyepiece are important. One could desire a diamond encrusted barrel with gold inlay but that's a personal issue and one would not expect manufacturers to support that market as there is no optical reason for doing so.
In the case of using Fluorite, I think it's very reasonable to ask the question whether the properties of Fluorite make it a good choice for eyepieces and Barlows. It maybe that the inclusion of Fluorite in an eyepiece would be a real disadvantage and result in an eyepiece that was a poor performer when compared to an eyepiece manufactured with more normal glasses. That is a question someone like Ernest can answer.
You may want an eyepiece made with Fluorite just to have one. I am indeed a practical man, I buy my eyepieces to view the wonders of the heavens above, those views are far from dull and lackluster. Indeed each moment is very special and magical... I guess I can be thankful that the thought of a Fluorite eyepiece is not necessary to provide spice and excitement to my time under the night sky..
if an eyepiece with Fluorite element(s) did offer an optical advantage, that would make it of interest to me..