Why a new Smalltalk?

Smalltalk itself hasn't changed much in 20 years.
Self and Strongtalk promised some change. We have Java instead, and slowly some change in the more traditional Smalltalk-80 implementations.
The commercial Smalltalks have customer bases to honor, existing investment, etc.
Squeak is self-hosted and malleable, but has too many small issues: new designs can't tackle all of them.
The right combination of ideas.

Smalltalk itself hasn't changed much in 20 years.