How do I remove the link element from the current page in a wp_list_pages menu?

Rewriting the entire walker class is a big pain… much more work than is justified for the result. But you can use a bit of javascript to remove the link. If you’re including jquery, something like this should work:

jquery(document).ready(function() {
    jquery('.current_page_item a').removeAttr( 'href' );
    });