I have a few theories.
One is that it's the other way around, society romanticizes the most common Therian breeds. It's possible that for so long Therians authors have written on occasion about their kind from a more fantasized point of view and thus influenced the modern day opinions of these animals.
Another is the dreaded idea that some of these "Therians" are roleplayers and not really Therians at all. I, personally, do believe in Therians however I also believe what a friend of mine said may be true; up to 90% of the people who claim to be Therians are roleplayers and it's possible, in fact highly likely, that not all Therians know what they are.
A third theory (and this I just thought up more for fun) is that you are losing your mind and simply imagining that everyone is romanticizing over the Therians. It won't be long before you hear creaking noises where there shouldn't be any sound and seeing shadows from places with no light... lol, joking, of course.
To be honest I think all we can come up with would be theories. Anyone who doesn't believe in Therians would likely tell you that people choose their favorite animal for what kind of Therian they are and then they roleplay the part, anyone who does believe in them may come up with a more thought through theory possibly resulting in some ideas like the two first ones I posted.
Hope this helps.