Here's the answer

April 26, 2020   photos  

The neutral line must remain unbroken so a path back to ground is maintained. In addition to this, neutral is the path to return the stream to the source, after doing its work. One more reason is that safety is the main concern as we mostly use our bare hands for bulb change. Hot wires control by switching not neutral no access charge. Another reason is that the phase wire is a current carry path and neutral wire current return path. That is why the Phase wire is a current carry path and neutral wire current return path.