Win32: No WS_SYSMENU when no title bar. But why?

When creating a window without title bar there's also no system menu. But why? I read the source files and found this:

	if( style&1 ){
		wstyle|=WS_CAPTION|WS_SYSMENU;
		if( style&2 ) wstyle|=WS_MINIMIZEBOX|WS_MAXIMIZEBOX;
	}else{
		wstyle|=WS_POPUP;
	}

What about changing it to:

	if( style&1 ){
		wstyle|=WS_CAPTION|WS_SYSMENU;
		if( style&2 ) wstyle|=WS_MINIMIZEBOX|WS_MAXIMIZEBOX;
	}else{
		wstyle|=WS_POPUP|WS_SYSMENU;
	}