That could be needed but I wouldn't remove the pistons unless everything else had been tried.
Usually the seals will last for years unless the wrong fluid has been put into the system.
If the brake lever comes to a hard stop when it is squeezed, no air has entered the system. If it feels squishy or spongy the system needs to be bled.
When the new pads are installed, a very light coating of special silicone disk brake grease should be applied to the two pins before they are inserted thru the caliper body and the two brake pads. Failing to do this can cause the disk pads to bind up and not to retract from the disk.
Don't use ordinary grease to lube these pins. If you don't have the right stuff it can be bought at a auto supply store and it doesn't cost a lot.
Another cause of the pads to hang up is if the spring is not installed correctly but this is usually noticeable when the pads are installed.
I know of one case where the hydraulic system somehow got too much fluid in it.
That also caused the pads to fail to retract but if that was the case here I would expect it to have been a problem before.
In any case, to elimanate this potential problem, remove the small rubber cap on the brake caliper bleed screw. Use a wrench to unscrew the bleed screw 1/2 turn.
If fluid squirts out, you have found the problem. If fluid just oozes out then this was not the problem.
In either case, after a small bit of fluid has come out, tighten the screw and reinstall the rubber cap. Do NOT get that brake fluid on any painted surface. It will soften and eat the paint.
Let us know what you find.