you're always suppose to know exactly what pin do what. You're the only one who can modify a pin to output (in theory) Sure you can use any kind of resistor bellow 10K. If your design use some Network Resistor and you have some spare in, why not using them?

Few extra i/o are still usefull anyways, just think what else you can do with. Calibration/Maintenance button, status output for XYZ stuff, list is long enough.

Out of curiosity, how many spare i/o do you have?