Sorry you feel that way!
The change happened for multiple reasons:
1. Performance. Loading multiple TinyMCE editors on the edit page/post screen was a resource hog and slowed down the page considerably when more than a few sections were added. Now, the TinyMCE editor only initializes when you open the section. Huge +1 for performance there.
2. More space. I can now add more options and even more tabs as time goes on without running out of real estate and making the page too long.
3. WordPress standards. The new sections use default WordPress functionality 100%, from the backbone JS modal to the metabox itself. The code is much better in many different areas, it’s a huge step forward.
I tried to make the UI as friendly as possible, adding a button for the content tab and settings tab. This means there’s only an extra 2 clicks (opening the modal and applying it).
I think if you give it a little time you make grow to appreciate it a bit more, especially the speed of it and once more options are added.
Really appreciate your feedback 🙂