I think the real problem here is the way it happened. Apps just stopped working about a week ago. There was no communication from Twitter whatsoever until this TOS change, and I wouldn't really call this "communication either"

It might make sense to stop supporting third party clients, but announce that something like that will happen instead of doing it unannounced and then ignoring all questions about it. It's their API, so they can do with it whatever they want, but this is really a dick move.