What is the upside for OSM if it changes licensing terms to be more amenable to those users? You say it is the tail wagging the dog, but you skip over why OSM should even care about capturing those users.
I realize that "funding" is an obvious answer, but I'm not real sure what that is supposed to look like. I also don't think the generic answer would convince proponents of the share a like terms (I'm personally ambivalent about share a like, but it's clear that a big chunk of the OSM community values it).
I wonder, could OSM even change their licensing in that way if they wanted to? Because all the contributors submitted their content under the old license, they'd all have to agree to the new license again, right?
No. Originally OSM was under a CC licence. In 2012, it was changed to the current ODbL licence. All the data from mappers who didn't agree had to be deleted. In order to map now, you have to agree to the "Contributor terms" which means the licence can be changed to any other "free and open" licence with a 2/3 vote of active mappers.
I realize that "funding" is an obvious answer, but I'm not real sure what that is supposed to look like. I also don't think the generic answer would convince proponents of the share a like terms (I'm personally ambivalent about share a like, but it's clear that a big chunk of the OSM community values it).