It's all about what makes sense for what I want to do.

I was pretty much done with toe clips after using them for a year and a half. On the other hand, putting on my clipless shoes whenever I wanted to take a ride was more hassle than I really wanted to deal with, so I bought a cheap pair of Wellgo double-sided pedals: one side clipless, one side flats. My commute is very short and I spend a lot of time on and off the bike, without a lot of time on the bike between stops (class to class just doesn't take that long). I've found that flats really are the best solution for short distance, just-get-on-the-bike-and-go riding. My singlespeed beater also has flats, for the same reason.

On the other hand, my road bike would be a lot less fun with flat pedals. Without clipless pedals, I can't stand up and really crank when I want to pretend that I'm fast. I also can't maintain a smooth, fast spin as easily without them. When I feel like riding that bike (which is often, it's a LOT of fun), I don't mind wearing my (walkable) clipless shoes. It's worth the trouble! But flat pedals are greatly, greatly underrated.