Mickey Mouse is not a very good analog to a typeface. The analog to Mickey Mouse would be a letter in an alphabet - an abstract concept, that, never the less, is immediately recognizable.
A typeface, then, is a specific set of instructions to a specific implementation of this abstract idea. I.e. with Mickey it might be a specification to a specific implementation of this character including the type of voice actor to use, how the character behaves specifically, how it moves, etc etc. I.e. a much more specific than just "It's mickey, it's ours, fuck off" type of obstruction of creativity.
Like I said, I have no idea if foundries and their license fees are necessary, but at least their clients know how to source a specific high quality implementation of their typefaces.
It seems to me that a font, suitable for printing, is a niche product with a very old history of proprietary providers and craftsmen.
It's this crafts aspect which makes the open sourcing a bit more difficult, IMO. I.e you need specialists to maintain a certain quality.