They have a corporate statement that is essentially meaningless.
While it may be meaningless in terms of practical application, it still articulates their wishes.
That's what hacks me off. There's a Starbucks I go to four times a week. They're fast and efficient, and they're good people. I like them. In fact, I like them enough to have made a point of speaking to the manager about their prior policy (the "carry your gun but don't be a jerk about it" one) and telling her I appreciated their support.
(I wonder how many of the black rifle lookhowcoolIam Open Carry folks bothered to do even that.)
Now, the corporate office has decided they don't want me carrying there. I suppose I could mumble "concealed means concealed" and bear in mind that there are no legal penalties for carrying anyway.
However, if I do so, I'm telling them that what they want is irrelevant to me, and that I don't respect them. You may not want me to belch loudly at the dinner table. There's no law against it, and I don't think you'd kick me out for it, but if you've made it clear you don't want it, I'll skip seconds on the bratwurst.
So, yes, there's something to be said for courtesy and consideration. A huge lack of both got us into this, and if I continue to frequent them without respecting their wishes, it feels pretty darned questionable.