How to set Active plugins as the default screen?

There are two options, modify the menu link href attribute or redirect the main screen.

Modify menu

Alter the global variable $submenu. This method works for Single and Multisite.
Problem: the submenu item Installed Plugins doesn’t show in bold.

add_action( 'admin_head', 'b5f_plugins_redirect_to_active' );

function b5f_plugins_redirect_to_active() 
{
    global $submenu;
    $submenu['plugins.php'][5][2] .= "?plugin_status=active";
    return;
}

Redirect page

Hook into load-plugins.php. Multisite detection is needed, but there are no UI problems.

add_action( 'load-plugins.php', 'b5f_ms_plugins_redirect_to_active' );

function b5f_ms_plugins_redirect_to_active() 
{
    // Trick, plugin_status is only false in WP default screen
    // ['action'] prevents us interfering with activation/deactivation 
    if( isset( $_GET['plugin_status'] ) || isset( $_GET['action'] ) )
        return;

    // Check for MS dashboard, redirect accordingly
    if( is_network_admin() )
        wp_redirect( network_admin_url( 'plugins.php?plugin_status=active' ) );
    else
        wp_redirect( admin_url( 'plugins.php?plugin_status=active' ) );

    exit();
}

---

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And a couple of extras:

1) Rename the main link to Active

add_action( 'admin_menu', 'rename_submenu_item', 99 );

function rename_submenu_item() 
{
    global $submenu;
    foreach( $submenu['plugins.php'] as $key => $value )
    {
        if( in_array( 'activate_plugins', $value ) ) 
            $submenu['plugins.php'][$key][0] = __( 'Active' );
    }
}

2) Add a submenu to access All

The submenu link is hacked, as well as some jQuery printed to fix the submenus active state:

add_action( 'admin_menu', 'menu_admin_wpse_44270' );
add_action( 'admin_head-plugins.php', 'highlight_menu_item_wpse_44270' );

function menu_admin_wpse_44270() 
{
    add_submenu_page(
        'plugins.php',
        'Drafts', 
        '<span id="my-all-plugins">All</span>', 
        'edit_pages', 
        'plugins.php?plugin_status=all'
    );
}

function highlight_menu_item_wpse_44270()
{
    if( isset( $_GET['plugin_status'] ) && 'all' == $_GET['plugin_status'] )
    {       
        ?>
        <script type="text/javascript">
            jQuery(document).ready( function($) 
            {
                var reference = $('#my-all-plugins').parent().parent();
                // add highlighting to our custom submenu
                reference.addClass('current');
                //remove higlighting from the default menu
                reference.parent().find('li:nth-child(2)').removeClass('current');             
            });     
        </script>
        <?php
    }
}