Clipless systems are specialist because you need special shoes. As utility cyclist, I may find myself wanting to wear waterproof winter footwear, formal black shoes for a business meeting, casual shoes for an evening party. I may want some footwear suitable for polished wooden flooring which may be damaged by metal cleats.
The dual spd/clipless pedals are one way to go, but then you have chose between pedal retension or not. I can chose any footwear with pedal retension. It suits my needs.