I've spent quite a lot of time now researching what I can find online about the story of how Ben Franklin assigned the terms positive and negative to what had previously been called vitreous and resinous, respectively. Ben thought that when he rubbed his glass rod with silk or wax that the glass was left in a state of having an excess of "electric fluid"[1]. He was also a proponent of the "one fluid" theory which we now know is incorrect because the electric field arises due to charge separation, not the "lack of electrons", but I digress.
Anyways, there are a bazillion tutorials out there about how we're stuck with the convention that was set by Franklin, but I have been completely unable to find out why this is. There is no trail of references that I can discern.
For example, the next major milestone after Franklin's use of the terms positive and negative in his experiments are probably Volta's pile experiments. In the drawings of his setups that I've been able to find on the internet, I see uses of the terms positive and negative, but there's no glass or wax involved in the voltaic pile. How did Volta select these terms? For that matter, how did every other 19th century experimenter implement Franklin's terminology?
To say that "Franklin set the convention and now we're stuck with it" is not good enough. There has to be a chronology, and a history of decisions amongst the prominent experimenters, no?
[1] http://www.gutenberg.org/files/45515/45515-h/45515-h.htm