Reddit could have just made third party client use a feature of Reddit premium and avoid all of the current issues. Yes, some would still complain that Reddit costs anything to use but big clients have paying customers and are less price sensitive.
Time: only a few weeks notice. They have to notify users of a change, make a plan, program it, apple approval for updates, and Apollo is just one guy with a part time designer.
Terrible communications. Say pricing would be fair and not like twitter. Say no api changes this year. Pretend to be fair. Deception .
They could have given Apollo and the many other apps that are shutting down a little more notice and time to adjust.
I think Reddit has its back against a wall and a VC gave an ultimatum/margin call that Reddit needs to make more money with a business plan in 30 days or no more funding re-up.