OP are you one of those people who are looking for something like this: Pin swapping in PCB?
I get the impression people who use devices like FPGAs where the pin assignment is very flexible want a feature like this to assign the most suitable pins.
Such a feature even if implemented would not be sufficient by itself in KiCad because wiring connection is by x-y location so just moving the symbol pins would change the circuit. The wiring would have to follow the pins to not alter the circuit.