If there is significant taper wear on any present or past pads, this tilts the piston slightly during every brake apply. Not usually a big deal, but over time, and especially if the taper is severe, this can damage the piston seal causing a leak, or even allow the piston to wear against the housing bore, which can lead to binding.
After you replace the caliper, pop out the piston, and look for signs of rubbing between piston and the machined-bore.
Piston removal:
Compress the piston before you remove the caliper, to push as much fluid as possible back into the system. After caliper removal, loosen bleeder screw and dump as much fluid as possible. Close bleeder screw.
If a twin piston caliper, you want to move the pistons out as a set. If you just blow with air in a single shot, 1 piston will shoot out, and the other will remain deep in the bore, with no way to build any more pressure.
With caliper "deadbug" on bench, place used pads and enough other flat objects as possible to fill gap between pistons and fingers leaving 1/2-1" gap. Fill gap with a shop towel. Use compressed are and a rubber-tip nozzle to push piston(s) out. Place a second shop towel over the piston area to prevent fluid spray in your face. Watch your fingers!! Remove the thinnest object in the stack and blow again. Keep going progressively until 1 or both of the pistons looses pressure. Remove that piston. The other piston should now be far enough out that you can wiggle it free by hand.