The release for the new version says "To simplify the experience, the Insert option has been removed from the right floating menu, as all insert actions are now easily accessible through the Quick Insert menu."
But they're not, really. After selecting text my options for inserting are reduced. I can't select and add a link or a glossary term, for example.
It's also much easier to have the Format/Insert/Content reuse menu continually visible on the right, so you can just select and click; instead of having to open the tiny popup menu.