> Other than maritime navigation, I can't think of many tasks where Mercator would be more useful than an equal-area projection.

Precisely why, I suspect, the US voted against the change. (One of the reasons, at least) I mean, gee, I wonder why the country with the world's largest navy* would prefer maps where you can draw a line on the map between two points and it's the actual compass direction? (Give or take a bit of weirdness near the poles, where the difference between the Earth's rotational pole and its magnetic pole actually matters in a way it doesn't matter below the polar circles).

It's just a symbolic vote, of course, and nobody's navy is going to stop using the so-useful-for-maritime-navigation Mercator just because of this UN vote. But still, I would bet that factored into the reasoning. How much? Who knows, I certainly couldn't say. Except to suspect that it was a non-trivial factor.

* Largest by tonnage — China and Russia have more total ships, with the US in third place by ship count, but the US has nearly half the number of aircraft carriers in the entire world, 11 out of a total of 23, and aircraft carriers are some of the heaviest ships out there. Numbers are from https://worldpopulationreview.com/country-rankings/largest-n...