Yes, I have. The officer should clearly state the reason for the request for identification, the reason I am being stopped, and whether he/she suspects me of any crimes (and if so, what, exactly), or what events I am thought to have witnessed.

I am a big nice man who, if carrying a gun, is doing so legally. Arrest is a very important line to cross. The police only have what powers we give them; the power to coerce identification is extremely limited.