Adding table classes to Drupal tables

Got this snippet from Twitter bootstrap theme

<?php
function tweme_preprocess_table(&$variables) {
  if (isset($variables['attributes']['class']) && is_string($variables['attributes']['class'])) {
   // Convert classes to an array.
   $variables['attributes']['class'] = explode(' ', $variables['attributes']['class']);
  }

  $variables['attributes']['class'][] = 'table';
  // $variables['attributes']['class'][] = 'table-striped';
}
?>

Shouldn't this be included in the template.php (Or the include files), or is there a reason why its not.