RSS would be a good query result format to add, so that wiki content can more easily be syndicated elsewhere.
As a Cargo user, I agree that it would be a good idea.
Currently I turn a Cargo query (with "ul" result format) into an RSS feed with the archived Extension:Bullet_Feed. That extension didn't work properly in the first place, and I've had to modify it with nearly every MW upgrade for years, so it would be easier to have this functionality built into Cargo itself.
Yes, I agree with this too! I don't remember anyone asking about this before, but (clearly) that doesn't mean that no one is interested in it. @Samwilson - if you're willing to create the format(s) for it, that would be great.
Is anyone still using Atom? Maybe they are; I have no idea.