Quote Originally Posted by InkstainedGwyn View Post
My suspicion is that a lot of the event items pre ~2015-2016 could be resold on the marketboard, and a lot of people 'invested' in items to resell later. That gives them less incentive to put them on the mog station, since they're competing with in-game currency. Also, I've noticed that while the new events all say "past event items may become available later", the old ones didn't, so it may come down to how it's advertised.
Eastern Cherry Tree

Was marketable, was expensive, added to cash shop as a non-marketable version. They have added the competition.