> No one in our industry seems much to teach this skill. I wonder why.

It's pretty simple. In a company of any size, customer support is a separate job from development. Asking a programmer to field support calls is like asking an architect to trim grass.

Yet, if they did so perhaps the architect would stop putting grass in places where it's too f'ing difficult to actually maintain properly. Sometimes putting the 'expert' in the shoes of the 'maintainer' works wonders toward creating designs than can actually be maintained.