I'd say that's a feature not a bug. Let iMessage roll out exploding balloons and whatever else they want in every update. I want to use my own client which should just stay compatible with the core functionality – sending lines of text back and forth.
And if they are deliberately breaking existing third-party apps for no reason, well I'm sure EU courts would like to have a word.
And if they are deliberately breaking existing third-party apps for no reason, well I'm sure EU courts would like to have a word.