SPJ also noted that the original success of haskell was due to their pursuit of laziness. Because laziness has no place in a system with side effects, their pursuit of laziness and functional programming is what led them to discover the usefulness of monads for describing it in the first place. If they were pursuing a strict language instead, then they were allowed to take shortcuts, because sneaking in side effects is a lot easier. YEs maybe the next haskell will be strict, but getting to the point to make that decision required laziness.

SPJ made a great lecture about this. It is very easy to follow and a fun insight into the academic history of modern functional languages https://www.youtube.com/watch?v=re96UgMk6GQ