@apolymask, thanks for the thoughtful responses!
The "extended" definitions of currency are definitely more generous than the "popular" ones... and yes, those could definitely include things like stocks and bonds, and pretty much anything "tradeable" that people could readily agree on a value of.
Ultimately "virtual money" (which is pretty close to what cryptos represent) makes more and more sense as we increasingly buy things from "virtual stores" and we even have more and more "virtual goods" like certain service and apps and such.
The reluctance exists in the "crossover" areas where people consider whether they can take their Steem or Bitcoin and buy a new couch. Which at the moment is somewhat limited-- or if not "limited" at least requires a level of knowledge and expertise that makes most people "on the street" a little uncomfortable.
But it's changing and progressing all the time!