Actually, there were clear instructions telling you to uninstall the beta client completely and then download the retail client from scratch. If you patch it, you could be asking for issues.
Actually, you're wrong. We were instructed that the client used in the Nov 25th beta weekend could be used at launch.
The post was lost in the forum wipe but I know I can find an article here on the website if you insist.
EDIT: OP has the link.