Our traditional editor toolbars have buttons to insert a [[File:Foo.png]] or similar, but not that would help you with the actual editing process.
A button that launches the UploadWizard -- possibly uploading to Commons -- and ends with inserting the image(s) into the article would be a big leap forward.
# User clicks on "insert media"
# In the dialog, user clicks on "upload new"
//… or 'User drags a file into the editor', see T40031 //
3. Dialog is launched
4. User confirms that the media file is theirs, and accepts that it will thus be under the default licence (CC-BY-SA-3.0); file starts uploading with a progress bar (indeterminate for now)
//… or user is directed to Special:Upload if local uploads are available.//
//… or user is directed to Special:UploadWizard on Commons.//
5. User enters a title.
6. User enters a description (default in the user's interface language, with a control to set the language to something else).
7. User optionally over-rides the date of creation from 'today'.
8. User optionally enters (Commons) categories.
9. User clicks "Publish and Insert", and file is un-gated on the stash and published on Commons, and inserted locally as a `thumb|right` (or `|left` on RTL) at default size with the description as the caption (if the description is in the content language).
//… or user clicks "Cancel Publishing" and the file is left in the stash for garbage collection, never published.//