Side effects are useful. We use them all the time: IO, graphics, sockets, signals, etc. We even use mutable data because in certain cases it's more efficient. So I think I agree with Yegge there wrt, "conservative."
Not sure if it was your intention to imply so, but neither Clojure nor Haskell* eschew side effects. However Haskell provides tools to manage side effects. I'm not sure about Clojure since I haven't dove into that pool yet.
* I mention Haskell since there is a lot of FUD going around about Haskellers not using side effects.
Nobody said that side effects aren't useful, as Rich Hickey would be the first to remind you. Clojure has full support for side effects and mutable data structures if you need it for efficiency. The point is that in Clojure, there are easy and idiomatic ways to control complexity by minimizing side effects and use of mutability.
