Things have come full circle for S&W.
When the hand ejectors were introduced, there were no square butts, only round.
Square butts were added a few years into production, and proved to be very popular.
Now they're gone again, with the option to use grips to "convert" a round butt to square (I've been doing that for years).
Surprising that this wasn't done sooner, as making two types of frames just complicates the process.