The "pin" issue may have been taken to a degree far greater than it's worth. That being said, symbolism is very important for anyone wanting to represent him/herself as a leader of this nation.

Leaders, and what they may do, are often interpreted not by just their words, but by their body language, dress, and general comportment. That's not just in the case of folk whose votes are being sought, but also by those whose actions (i.e., foreign leaders) may be influenced by them. There is an expectation that the leaders of this nation will appear at official functions in the "corporate uniform" of the job, and (for example) not wearing the equivalent of a leather vest, jeans and cut-away gloves (my preferred wardrobe). For the Chief Executive, over the years it has become customary to display a lapel flag-pin (Democrats and Republicans have both done it) as a matter of unity and national pride.

The candidates are representing themselves not only to the voters of this country, but also to all foreign leaders as well. How the candidates act, react and display themselves is indeed being evaluated outside the US, and within by every embassy and foreign mission that is resident here.

That's just the way it is.....