Methods place(), pack() and grid() correspond to corresponding Tk commands. These commands return nothing (empty string) in Tk, and Tkinter methods return nothing (None) in Python. If they will became returning something meaningful in future versions of Tk, we will lost a chance to translate this to Python if make them now returning the widget itself.

Note also that method chaining is not commonly used in Python. This code would look pretty unpythonic.

For these reasons I am against this idea.