Ernest my dear chap, even if your instrument doesn't need tuning it is a 'bit of a bluff' to pretend to tune very slightly and connect with your audience. Be light hearted, joke, build up a background to your songs etc. Lighten up man! few if any artist will go on stage to perform if they don't know their instrument! Suicide at its best!!
Oh! and by the way, I know my instruments inside out and I have to tune one of them or check the instrument between every set or should I sing then before I play again I usually need to retune (it only takes a few seconds)I talk to the audience as I carry this out. Uilleann pipes are not an instrument you tune once and thats that!
Give a bit of slack to the 'artists'who have broken all your (rules) or guide lines and found it works for them.
I do not disagree that you have a few valid points BUT don't be too rigid with them. They may work for you, if so, stick with it!   Very good thread!
               OH (old hand)