How to hide editor, but keep media library access

Question

The media_upload_tabs filter passes a single argument containing an
array of the tabs, you can unset() them to remove them.

The array looks something like this:

Array
(
    [type] => From Computer
    [type_url] => From URL
     => Gallery
    [library] => Media Library
)

to remove the media library tab:

function remove_media_library_tab($tabs) {
    unset($tabs['library']);
    return $tabs;
}
add_filter('media_upload_tabs', 'remove_media_library_tab');

If you only want to hide it on certain posts or post_types you can check the $_REQUEST or $_GET args. When using the ‘Upload/Insert’ links several points of data are passed along: /wp-admin/media-upload.php?post_id=28506&type=image&TB_iframe=1&width=640&height=581

function remove_media_library_tab($tabs) {
    if (isset($_REQUEST['post_id'])) {
        $post_type = get_post_type($_REQUEST['post_id]);
        if ('post' == $post_type)
            unset($tabs['library']);
    }
        return $tabs;
}
add_filter('media_upload_tabs', 'remove_media_library_tab');

Hope that helps