Getting rid of Mercury creates the same problem that is angering folks about the new seasonal content: they'll be getting rid of stuff people have paid for. Mercury came in the Curse of Osiris DLC. Like Io, Titan, and Nessus, I think it just needs a fresh coat of paint. The new 2.0 system helps, but so would seasonal refresh of their vendor items. This is why I'm excited about what the Vex Invasions might be. Random Vex public events across the solar system would give me a reason to go back to places like Io other than farming resources. I'm also going to point out that nobody knows what's actually in the new seasons. We'll have to wait and see.