Hi Mary, thanks for your comment. The survey is (mostly) meant as an initial foray for getting an overview and help us figure out general trends and concerns. It's definitely not the end-all for all feedback, but a first step; so the input we're receiving now will shape and inform future rounds (although they will definitely not be as massive in scale as this one!)
In other words, we will absolutely look into asking more project-specific questions at a later date (for example, regarding tagging.)

The website questions, in marked contrast, are so detailed because Webmasters are planning a redesign of the tw.org presence for this year, so they had an immediate and concrete need because they are getting started on this right away.

(The 15 minutes estimate is the average we got from our test group.)