The concept is low-priced stores and outlets rather than a mainstream lineup. Actually it did poorly, at least it was doing poorly last we heard. The last one was the Supermall in Auburn in the early 1990s or so. There is simply no land at the right price.
We don't build new regional malls, period.
Not in big ways like adding towers, but in still-important ways - adding new wings, and doing so by replacing some surface parking with garages.
The interesting thing about Seattle's suburban (and inside Seattle) shopping centers is that most are densifying.