Annotation removal. Not understanding the problem

They said in their release that all the old annotations will still work, I like the table of contents idea, I never saw that used before but it would have been great for some tutorials I am working with right now(50min blender tutorial on how to logo)
The reason why people are flipping a lid is because all of their content has annotations at the end. It is honestly what the end screen is based on. And the best thing, it works like a charm across all devices!

youtube isn't removing existing annotations. You just can't add new ones. They said so in their blog post.
I think removing the annotations system is actually a good thing since they don't work on mobile anyway and 70% of my audience (and probably the audience that the majority of people have) == mobile users.

That said I do hope they add some of the features annotations had into cards. Things like showing text on screen, or highlighting a certain area of the screen, etc would all be useful for those times where you remember something you forgot to mention only //after// your video is already uploaded and released.