A. Add to any toolbar the Text, Edit ... button (using CUI).
B. If you can do dimension edit frequently you can assign doubleclick to dimensions in order to edit text:
1. CUI + enter.
2. Double click actions > Dimension (default action is Properties).
3. Drag on top of Dimension the Mtext Edit...command from Commands List.
Now, when you double click on a dimension it will bring you the edit text.
I still do things the old school way... to a point.
When I need to edit something with text in it I just type DD at the keyboard (lisp routine attached) and select the entitly. The lisp routine is smart enough to "see" what kind of text entity it is and opens up the appropriate dialog box.
It works for:
This still beats having to find an icon somewhere on the ribbon (less effort).