Nexon's decline in traffic

That may be true in private servers but I doubt it on the live game, at least not to the extent you've said.

Mob life and props won't spawn until a player has entered for the first time, but the map itself has to be preloaded for them to be able to enter in the first place without excessive delay, and once a player has entered and initialized the map it never despawns it so that map on that channel has become permanent overhead until the next SC, even if no one ever enters it again.

They could do garbage collection to tick off how long a map's been empty and start deallocating it after a certain threshold but that means more CPU to unload it and reload it, and more potential memory leaks for an area that gets passed through regularly but not too regularly.

You've said what I meant to say, just more eloquently. Thanks

All in all, then, it clearly would be beneficial for both Nexon and the end-user if they removed useless crap like Coke Town. So the question is, why don't they do it? Andddd I think I know the answer.