One of the main advantages of cycling shoes is that they have a very stiff sole, which act to distribute the force exerted by a pedal stroke over a wider area of your foot. Clipless or not, cycling shoes are stiff. The bottoms of your feet won't hurt as much with stiff soles.
For me, I can't ride a bike without my feet being clipped in. I started using "rat trap" cleats in the late 60's and have used some form of being "clipped in" ever since. The very few occasions when I did ride platform pedals without my feet being attached to the pedals was a very unsettling experience. I felt naked. Like driving a auto without the seatbelt being buckled. In addition to not being able to pull up on a back stroke, I felt like I could easily lose control, or that my feet would accidentally slip off a pedal at any time, especially when going over those inevitable bumps in the roadway.
Sure, I've fallen a few times when I couldn't get un-clipped fast enought. Once in junior high school, at very low speed coming out the school driveway and turning onto the street where there was a patch of sand. Front tire slipped out from under me. The other time was when being chased by dogs on a sand/dirt road during my cross-country cycling trip in 1995. That's all I can remember. At faster speeds, I see it as a safety hazard if I wasn't clipped in somehow.
p.s. 1) There are pedals available that have clips on one side and a platform on the other. Then, you can ride clipped-in (with the appropriate shoes), or push the platforms using any shoe you want.
p.s. 2) As mentioned by jmccain, most pedals come with cleats. Keep in mind that there are several varieties of cleats available. Those that come with pedals usually have a float. That means that you can twist your ankle a few degrees side-to-side without unclipping. Since my history of being clipped-in is so long, and that most of that time have been in "rat traps", I have never gotten used to float cleats and ride with no-float cleats instead. That just means that I can't twist my ankle without un-clipping. Those no-float cleats have to be purchased separately. Figure an additional $30. (Anybody want to buy two sets of brand-new Shimano SPD-SL float cleats?)