We aren't just making TinyMCE look the same as Atto. The path we followed when developing these themes etc was:
- Take the icons from TinyMCE 4 and back port them to TinyMCE 3
- This will make it less jarring when/if we do migrate to TinyMCE 4 in the future
- Take the icons developed for TinyMCE 3 and apply them to Atto
- Make similar icons for the PDF annotation plugin for Assignment module
- Add extra UI enhancements to the PDF annotation plugin for Assignment module
- Replicate those UI enhancements for Atto
- Decide that the UI enhancements should be used to unify the whole of Moodle's toolbars, TinyMCE and Filemanager/Filepicker included.
- Match TinyMCE to Atto
As you can see it's not just a case of make all the editors the same. It's about providing a standardised and familiar UI across Moodle, something we have lacked for a long time now.