I understand the reluctance to generically encourage something that does not always arise.  With Nick's promise to help examine any particular problems with deletion of tkinter modules, should they arise, I feel comfortable closing this. I already tested and applied double deletion to both 3.5 and 3.6.

The tkinter import example illustrates potential benefits from refactoring (which I will continue in #27534).  For me, on Win10, 'import tkinter' in a fresh interactive interpreter boosts 'len(sys.modules) from 41 to 65.  Except when run cannot start, it only uses tkinter to call _tkinter.tkapp().eval('update') in its interactive input loop. Importing _tkinter instead (a slight risk) would not import anything else.

Guido: when I need help with some of the more obscure IDLE code, I will ask.