See, this shows how much I know. I think I might have been able to score a part in Spartacus!
The first time I went looking for a suit at a thrift store (less than 2 years ago) I was able to find a linen blend suit priced a $6.00. I thought I had a great deal until I got to the check out and found out that it was reduced to $3.00. I was hooked. Last week I picked up by fourth thrift store suit although this one cost me $10.00, which is the most that I have made to date. True, you are not going to be able to walk into a thrift store the first time or every time and find a suit that fits. Shopping and finding clothes that fit means that you have to go shopping on a regular basis.
Since I have been in the working world (40 years) I have at various times worked in offices that required professional attire with the typical 'dress down' Fridays. Now it seems as though, in these same offices, a shirt with buttons is professional attire. I see a number of men come to work wearing tee shirts, cargo shorts and flip flops. They can wear whatever they want, but if they were my supervisor I would be asking myself, "What did I do wrong that he is my boss?"
So, ignoring all of the other talking points, I find it very hard to believe that dressing well actually makes you more productive. Not everyone shares the same ideals as most of us do and couldn't care less about a well fitting pair of trousers. I've worked with some brilliant people in my career who dressed terribly. I don't buy that, if they threw on a nicer outfit, they would be better at their job. In any way. Whatsoever.
While I agree with pretty much everything you said, I'm going to pedantic. It *does* require more effort to dress well. Washing clothes becomes more tedious (often can't use a dryer for many items, dry cleaning). You have to iron your clothes. You have to *think* about what you're going to wear. It also costs significantly more, even if you buy cheap. Hard to beat the price of a T and sweats from Wal-Mart.
That said, I still agree; dressing well is not solely a display of vanity.