Bit of a rant about single-piston calipers used on mid-sized and big Mopars

This is all entirely by design. The instant you increase the angle in the piston seal groove that controls the deflection (and therefore retraction) of the seal and piston, you'll be here complaining about excessive pedal travel. Been there, done that.
(Fyi the groove in the caliper for the seal is not rectangular, it is trapezoidal)

Additionally, the runout of the rotor and deflection in the wheel bearings aid in kicking the pads out. If the pads are truly dragging, you'll smell it in no time.

This is precisely why A12 cars and drag racers use drum brakes.

Smaller pistons and rings have better control over this, so a four piston caliber might be of benefit.