I find it interesting that Rich (and other Clojure people) feel they need to continue defending themselves again and again. While strongly typed language communities usually don't feel the need. There must be some deep doubt in the Clojure community that triggers this.
I think it's more a acknowledgement of the current state of popularity of languages and an attempt to win people over rather than a manifestation of latent doubt.
Forgive me, but your comment seems a little disingenuous with the way it generalises the static community (every static language??) vs the clojure community.
Many of the comments on this page show why Rich gave the keynote. Because the same advantages of type checking are put forward as a reason to not use clojure over and over. They're not wrong, static typing has advantages, but I see little acceptance of any tradeoffs (or even acceptance that such tradeoffs exist: concretion of information, coupling of distant components by shared types etc etc etc I'm just paraphrasing the keynote).
He was highlighting the value proposition and tradeoffs of: being data-oriented, being dynamic and clojure.spec niceness. He felt the need to do this because he clearly felt that some people who were wavering about clojure were unsure why it was dynamic: "can't we have all this great stuff AND static types". He wanted to say "yes quite possibly you could, BUT here's the reasons why I didn't add types".
