I'm going to throw my 2 cents worth in on this because recently I've gone 180 degrees from what I used for the past 41 years of cycle racing (road and MT.), touring, etc. Like most folks I had the same hard and fast assumptions relating to what a "serious cyclist" would use and have always assumed that one had to use cycling shoes with clips and cleats (in "the old days") or clipless pedals/shoes. After reading an essay by Grant Peterson recently at rivbike.com on the myth of cycling shoes, I decided to give it a try, an lo and behold, he's right! I don't need cycling shoes. Wow no more geek shoes. I can wear my Keen non spd sandals and ride in perfect comfort with a full load (30-40 lbs) in the mountains and still crank out 80-100 miles a day. My knees feel better because I'm not limited to a measly 5 degrees of float. My foot can find it's most comfortable/ideal position on the pedal. Better for the knees. I still use spd pedals with my recumbent because I'm reclined at a 30 degree angle, and if I still raced, I'd still be clipped in, but I'm not. I'm touring at a 10 -15 mph pace, not racing. I don't pull up on my upstroke and neither do you, unless you are sprinting. To paraphrase Tom Hanks in ":A League of Her Own" : there's no sprinting in touring!
The thing that nobody has mentioned in this thread is you really need to use a large platform pedal to provide the stiffness that a cycle shoe normally would, like a lambda MKS or a Tioga spider, or Speedplay Drillium. Comfortable, grippy, and when you get off the bike you can look like a normal person. As a cycling advocate when I'm touring this is important to me as I feel I am able to connect more easily to regular folks by riding in non cycling clothes and shoes. In all the years I was a cyclist, my identity was connected to being seen as a "cyclist" and as such enjoyed being different from all those "non-cyclists" by wearing the requisite lycra "costume" which I think can create an us vs. them mentality and by wearing looser fitting, fast drying synthetics and wool outdoor clothes that look more normal, I find that more average folks on my tours talk to me and am more approachable. These same folks may be more inclined to consider serious cycling as an option if they can wear more "normal" clothes. I guess I'm getting into a new thread here with the clothes but I do think it's related to the shoe thing. Don't assume that all dyed in the wool cycling assumptions are the only truth. Try something new, you may be surprised at how freeing it is!