The enhacned text text datatype for the richtext widget is what triggered the linking of URLs.
Actually it should work for text/plain or text/enhanced looking at ad_text_to_html.
Anyway I think using the format of text/html is what causes the links to not be converted.
The link parser is smart enough to not link urls that are already in a tag so it is probably possible to detect links inside html content and convert them.
