There is this option: "Return Playhead to Start Position on Stop" already.

But I wonder why it couldn't work like it works in After Effects? It's a bit confusing to have different ways to do the same thing depending on the Adobe application. Especially when you work with these apps the same time (dynami links and so on).

After Effects:
'Space' key stops the Playhead
'Escape' key returns Playhead to Start Position on Stop