Until "expressiveness" has a defined meaning, I encourage us all to stop using it to describe programming languages. We just beat each other up with it without really saying anything meaningful.

Programs that were right before continue to be right. Programs that were wrong before continue to be wrong. What's changed is that programs which were wrong before can now be wrong at runtime rather than at compile time. The parts of the program that don't explode now wouldn't have exploded before. So I don't think that really changes the expressiveness, whatever that means.

I think this change will do wonders for Haskell marketing but I don't think it will have much effect on the day-to-day lives of Haskell programmers.