Currently, I am in Thailand experiencing the culture and learning about how other, often slimmer, cultures live and experience life. One thing I have noticed while here in Thailand is the posture of the locals. It is near perfect. In the US, it is very rare to see so many people with great posture.
Two of the things that really seem to make this posture to attainable is the absence of shoes. Many people here go bare foot or wear sandals, which are as close to nothing as you can get. I haven't seen a case of flat feet in any of the bare foot walkers I have seen. The toe separation and foot control is amazing.
Personally, I have noticed my feet and posture improving in only a few short days of walking with flip flops. My inner groin and arches are a bit sore, which I attribute to years of atrophy from casting my foot in traditional shoes. Research has pointed to barefoot walking as superior to shoes for years, and countries like Thailand, where barefoot walking is very common, prove this.
The second major difference with posture I noticed is the mid trap muscles. They are highly developed in many of the people. Mostly the men, as you see them without their shirts on. This is something you simply don't see in the US. People are so slouched and forward dominant it is far more common to see atrophied mid trap muscles than developed. The middle trap muscles hold the shoulder blades closer to the spine, creating a healthy shoulder and upper spine.
At this point in time, there will not be a change in shoe wearing in the US or other developed countries but we can make a concerted effort to strengthen our feet and spend as much time as possible barefoot or in minimal type, toe freeing sandals. The whole notion of not wearing flip flops because they are bad for you feet seems to be defeated here in Thailand. From my personal experience wearing flip flops seem to be helping my feet activate better. Wish I would have done this years ago.
Try a week barefoot or with flip flops and see what happens. Maybe you will have a similar experience.