This is fine, if there would be a nice documentation for new version. There wasn't, except for some scattered blog posts.
This is fine, if new version offered some exciting new features or simplified thing a lot. But no, everything became significantly more complicated.
This is fine, if Babel was a production library packed into final build, and modularity is necessary to save precious bytes from web-transmitted JS. But no, it is a development tool. Nobody cares about its size or one-size-fits-all.
I just don't understand. What is the use case that required such a big sacrifice?