BS”D
Those are the standards of proper dress even in the secular world, especially here in Europe. If Torah men and women are living up to only the lowest common denominator in dress standards, then what kind of a message does that convey?
I once dealt with a self defined “Orthodox” so-called businessman in NY who walked around his office in shorts and flip flops (no, it was not a software or Internet firm where this kind of thing is considered cool). That was an immediate tipoff to me that he was a disrespectful, rude, silly jerk, and right I was.
Here in Europe, not wearing socks altogether is considered OK only among teenagers and women who are frankly advertising themselves in public, if not for money in the form of at least a paid for date, then just for attention from guys. Doing that for attention appears to be the essence of “naval birshus haTorah”, plain and simple. Doing it for comfort has its place, maybe in the mountains or at camp for both genders, but is it how we want to present ourselves in most settings?
And men dressed that way are usually students who will outgrow it as soon as they start working for a living.
Those shaitlach are another issue altogether and a psak halacha is needed.
As for davening mincha at a rest area, especially if minyanim are organized, that is elevating the rest area to a mokom kodosh and is therefore admirable. I davened in a mall when I was once caught off guard by early mincha times in a northern city, and that was the exact feeling I had when I did it.