It’s just design by committee and long-standing efforts for backwards compatibility. Also the people writing the standards are far too familiar with them and thus a bit lost when it comes to making practical decisions.
Whenever you make changes there will be compromises and someone will have reason to be unhappy.
There is no way that eliminating 2.0, in such a way that everything that used to rate as 2.0 now qualifies as conforming to some subset of 2.1, can be justified as backwards compatibility.
Whenever you make changes there will be compromises and someone will have reason to be unhappy.