This gesture to switch the focused app was already a bit of a
compromise solution at the time it was added, its clunky way to
work (3fg long press, then taps with a 4th finger to switch
application) was pretty much picking up the remains of our
limited wiggle room (sticking to 3fg/4fg global gestures, since
2fg are application domain).
But then directional 3fg gestures took prevalence, and made it
easier to switch between applications. This small gesture remained
a bit of an easter egg, largely unused and unknown.
Fast forward to today, and it's being noticed in a bad way. The
changes to event handling and delivery to actions has made this
gesture take prevalence over the wee-bit-more-popular 3fg swipe
gestures, making those never become active and never trigger.
While a gesture framework is being investigated that might
help handle these situations (or, in a less undefined manner),
this doesn't seem like a case worth going out of our way to
hack around until that is in place. We can remove this, and make
all WM interactions go through the 3fg directional gestures.