[tytso]

- users always want faster, more direct answers (rather than controlling the filtering/categorization of their searches)

That's a very power-user centric attitude, don't you think? As a power user I preferred to type long, complicated Sabre queries to find exactly which airplane flight I wanted. It was much faster, and I had memorized all of the complicated mnemonics. But that's not what a casual user would want to use.

Asking users to specify categories for what they want means requiring a certain orientation in their thinking which is shared by computer scientists and trained librarians. But to an average user, that's extra work. And think about how this might work if you're talking to an actual human librarian: if you start asking about TV shows, and then mention "The Big Bang Theory", do you think the librarian will ask you, "Did you mean the scientific theory, or the TV show?" That's only something a stupid computer would do. A smart librarian would take the context of the previous queries that you've made of him or her, and provide the right answer quickly and efficiently. Wouldn't you want the same thing from a search engine?