No, this is not a reason to do an update URL.
DMOZ only records the URL, the category (ie the topic of the site), and the (usually) editor-created title and description (also the topic and general contents of the site)
As long as it is in the correct category, has an accurate title and description, with the correct URL, there is no need to request an update.
Changing color schemes, adding meta tags, rearranging the content are all things that you can do to your site which 99.9% of the time gives no reason to request an update.
Moving the site's loocation or changing the focus of the site are two reasons why you would want to submit an update request.