I'll take a whack and put my .02 cents in. I know that my opinion doesn't mean much in world circles, but here it is.
I believe an artist is an artist no matter what their medium is. If you can turn something into any form of art that others find interesting then you are an artist. Some have years of training and some have no training at all, just plain luck. I know a few that can pick up a pencil or stylus and go to town. In leather work, if you take the time to study and understand your mediums it would certainly help you develop certain skills necessary to better your craft.
Being able to work with all types of leather in different formats (plain, carved, painted, embossed, inlay, applique, etc) would certainly make you versatile. As a person, I believe you call yourself what you like. I am a hobbyist, but I do not mind being called a Craftsman, Artist, or newbie. The only term that I do not accept at this point is Master because I feel that I haven't learned enough about my craft to be one nor am I good at one part.
Interesting thread.