BuddyPress.org

I disagree. Using the BP Template Pack and building as a child theme of BP-Default have their respective advantages and disadvantages.

An advantage of using the Template Pack which I feel you’re overlooking is that it allows theme designers to quickly get the required template/css/js files into their custom theme. This is a lot quicker for a non-BP-expert than figuring out which files are required. The designer then has two options; add, possibly duplicate, your CSS to style the BuddyPress templates to match the rest of the site, or use the Template Pack files as a skeleton, which the designer can then use to rebuild those templates to their own HTML/CSS specifications (perhaps to use a theme framework).