Normally there is a strategic purpose for a site, which dictates what the site is trying to achieve first and foremost. If the site is aimed at users trained to properly operate the site, then there is no question that functionality is paramount. A site aimed at the general public had better focus on usability because consumers do not feel like having to be trained before they can access a web site. Of course, regression does not fit into the equation at all: this has to do with incremental changes to the website logic. No, DB is only one of the ways to provide content, it does not alter the focus of consumer vs. trained user. It seems to me that you are confused about what is needed to establish testing priorities by thinking of it in a web user context: ultimately there shouldn't be a difference because the system has to work in the correct manner and in a user-friendly manner at the same time.