Interesting point about the relative value of typing vs. testing, and how too-strict typing can crowd out testing. However, see the discussion under pixie_'s comment about new code vs. refactoring.

Also, this makes me think about incorporating testing directly into the language, which kind of brings us to Design By Contract and formal methods. It seems to me that now would be a good time to resume active research on those things, instead of all these exhortations to use magic type systems and magic immutability and so on.