I would agree that an "Ideas" icon, should be made available, so that a USER may decide that they want that icon, in THEIR customized toolbar layout..
Of course, mozilla updates, and new versions should respect all USER options from past versions... At present, seems USER option choices are randomly honored... not very friendly.
I agree, new versions must respect all user options of previous versions, this should not change, just suggest a more functional toolbar and no dead spaces by default.