Disney wants people pre-booking FP+. While some "day of" access might occur in the future, the entire business case of FP+ is predicated on everyone having FP+ reserved before stepping foot into the park, thus encouraging people to pre-plan their vacations.
So, I don't see what the purpose of paper FP machines would benefit, even if they were RFID enabled and linked to FP+. At that point, why not just replace them with more FP+ kiosks so you can book a ride for anywhere in the park without running to a ride? That would work more or less as well as old style FP machines, even if people are able to get additional FP+ the day of beyond the 3 pre-booked ones.
Also, Disney wants to save on the printing costs of the old FPs. They want it all electronic.