Actually, I was originally of the same opinion, but then I read some lecture slides from Simon PJ. He has suggested that laziness was perhaps not the best default. It is hard to reason about space leaks with laziness. Likewise for typeclasses being inferior to ML functors.

http://www.cs.nott.ac.uk/%7Egmh/appsem-slides/peytonjones.pp...

I personally disagree. I'm pretty sure laziness has made it much easier for me to try out an idea. If it works, then I'll test that I didn't space leak. The notion of it almost makes me feel dirty. ;-) :-P