Professional artists of all ilk share a common problem: they need the money from patrons and/or clients (PoC), but don't really need their input—which they invariably give. Since the PoC pays the bills, the artist has three choices. Let's look at them carefully.
1. Forestall all input. If you can make this work, tell me how. Especially in a capitalist system, the guys with the money not only have The Say, they are perfectly aware that they have The Say. They expect The Say. They are upset by any suggestion that they don't have The Say. Additionally, they want pride of ownership, to feel that they were more than just the money behind something beautiful. No, they will make suggestions, even if such things are proscribed.
2. Explain why the PoC's particular suggestion isn't good. A master politician can explain away suggestions without the PoC even noticing it, but this is advanced stuff, not for the initiate. Any counterargument runs the risk of insulting their sense of good taste. This is not such a good idea since it was that same sense of good taste that made you their artist in the first place. No, artists generally want to lie and make their PoC feel as if they were perfect artistic peers—as if the PoC was equally talented, just lacking the time to do it themselves.
A followup problem to this approach is that if you successfully explain why this particular suggestion is not so good, another is sure to follow, and quickly. As the artist continues to rebuff one after another of their suggestions the PoC will grow suspicious, and suspect the horrible truth, which sours the whole deal for everyone. The threat of this ends up resulting in...
3. Relent and make the suggested change. Of course, assuming the artist has shown what she believes to be the best possible design, this suggestion will always, always be for the worse. It corrupts her vision and makes her resent the PoC, her situation, and the diluted end result. She is not proud of the work and others, upon encountering it, will smell its dilution, its suboptimal-ness.
What to do? Well, I've been coy. There is a fourth choice.
This suggestion came from my professors in my undergraduate graphic design course—perhaps unknowingly imparting to us a means of manipulating them. They were our PoCs, you see.
4. Add the gorilla hand. The artist must make the thing perfect for herself, for itself, for the Ages. Give it the quality without a name. Make it OM. And then, add something so ugly, so obvious that even the dullest of PoCs will have to take note and take offense. The canonical example is a gorilla hand. Imagine it dangling from a Calder, whirling amongst the abstract, primary forms. At a review the PoC will have no choice but to say,
"It's perfect. I love it. I love you. I love your work. I love every, single part of it, except...and I pray you'll forgive me...Oh I'll just say it: The gorilla hand. I know that it is your vision, but if you would permit me this tiny consideration, I think that...if you just imagine the piece without, it would be perfect."
At which point the artist must look at the work, tip up her head, engage in deep consideration, perhaps move about it, and finally reply,
"You know, you're right. I would never have seen it. You have made this thing a work of beauty."
This works for many media, not just kinetic art, but graphic art, website design, writing, interaction design consulting, maybe even interpretive dance. Try it in your medium and let me know how it goes.
Three addenda. First, the artist must be prepared to explain in all earnestness the reason why the gorilla hand is there in the first place, with the same conviction and language as she might explain the rest of the work. This way the PoC will not suspect that he is being manipulated. Second, and for similar reasons, the artist will have to tailor the obviousness of the hand to the cleverness of the PoC. If it's too obvious then the smart ones will clue in, and the jig will be up. Finally, the artist utilizing the gorilla hand technique runs a huge risk, i.e. that the wrong thing will be noticed, ("Oh I just LOVE the gorilla hand! But about that color red...") but in such cases I would first blame the hand. It was not gorilla enough.
I never, ever do this with any of my clients.