What is the purpose of this code?

  if ($element['#size'] >= 15) {
    $element['#size'] = '';
    $element['#attributes']['class'] = isset($element['#attributes']['class']) ? "{$element['#attributes']['class']} fluid" : "fluid";
  }

It makes all my textfields tiny. Are you meant to say input.fluid { width: 300px }? If so, why not just do it if the size is not set, or the size is the default (60 i think?)