Wordpress - How to limit wordpress menu depth in admin panel

The solution that I came up with:

/**
 * Limit max menu depth in admin panel to 2
 */
function q242068_limit_depth( $hook ) {
  if ( $hook != 'nav-menus.php' ) return;

  // override default value right after 'nav-menu' JS
  wp_add_inline_script( 'nav-menu', 'wpNavMenu.options.globalMaxDepth = 1;', 'after' );
}
add_action( 'admin_enqueue_scripts', 'q242068_limit_depth' );

Follow up on @jmarceli's and @squarecandy's great answers. Here is a solution that allows for:

• Easier scaling (set an object in the php action)
• Updates to the correct menu depth when the location checkboxes are changed

/**
 * Limit max menu depth in admin panel 
 */

function limit_admin_menu_depth($hook)
{
    if ($hook != 'nav-menus.php') return;

    wp_register_script('limit-admin-menu-depth', get_stylesheet_directory_uri() . '/js/admin/limit-menu-depth.js', array(), '1.0.0', true);
    wp_localize_script(
        'limit-admin-menu-depth',
        'myMenuDepths',
        array(
            'primary' => 1, // <-- Set your menu location and max depth here
            'footer' => 0 // <-- Add as many as you like
        )
    );
    wp_enqueue_script('limit-admin-menu-depth');
}
add_action( 'admin_enqueue_scripts', 'limit_admin_menu_depth' );

js

/**
 * Limit max menu depth in admin panel
 * Expects wp_localize_script to have set an object of menu locations
 * in the shape of { location: maxDepth, location2: maxDepth2 }
 * e.g var menu-depths = {"primary":"1","footer":"0"};
 */
(function ($) {
    // Get initial maximum menu depth, so that we may restore to it later.
    var initialMaxDepth = wpNavMenu.options.globalMaxDepth;

    function setMaxDepth() {
        // Loop through each of the menu locations
        $.each(myMenuDepths, function (location, maxDepth) {
            if (
                $('#locations-' + location).prop('checked') &&
                maxDepth < wpNavMenu.options.globalMaxDepth
            ) {
                // If this menu location is checked
                // and if the max depth for this location is less than the current globalMaxDepth
                // Then set globalMaxDepth to the max depth for this location
                wpNavMenu.options.globalMaxDepth = maxDepth;
            }
        });
    }

    // Run the function once on document ready
    setMaxDepth();

    // Re-run the function if the menu location checkboxes are changed
    $('.menu-theme-locations input').on('change', function () {
        wpNavMenu.options.globalMaxDepth = initialMaxDepth;
        setMaxDepth();
    });
})(jQuery);