We are planning to introduce both SVG and canvas rendering in a future update of the diagram. The IDs were removed with the implementation of the canvas rendering of the diagram, because its engine does not use them. I logged a feature request for bringing them back, which you can use to track the status of this feature, vote for it or comment it: http://feedback.telerik.com/Project/108/Feedback/Details/143799
The text editing of shapes and connections was removed, because we are working on an enhanced version of this functionality that is not yet included in RadDiagram.
Note that the diagram control is still in Beta. Its official release is scheduled for Q1 2015 and it is expected to encounter such changes in its functionality until it is finalized.