I think a cyclist should first select the shoes, then the pedals to fit.

A lot depends on your cycling style. If you're like me, and your touring day consists of 14 or 15 hours on and off the bike, with less than eight hours of actual cycling, and a lot of walking and hiking around during the day, a flat walking shoe may be preferable to a cleat. On the other hand, if your cycling day is over after four or five hours in the saddle, you may want to wear cycling shoes and carry an extra pair of town shoes.

Another factor is cost, for some. I see some pedals and shoes that cost more than I would (or could) ever spend on a bike.