> So now, even if the operation finishes instantly, we show the animation, wasting the user's time.
I thought it was fairly well accepted that small deliberate UI delays (for things like loading spinners and animations) can in many cases result in a better user experience. Of course, that would depend on how long this animation is that you're talking about.
You're absolutely right, in some cases. It depends on who you are and what kind of software you use. Delays or animations can improve communication between the UI and the user. Or, they can be pointless and frustrating, e.g. if the software's task feels utilitarian, and there's no confusing or hard-to-perceive transition that an animation would help to bridge, and the user knows the animation is functionless.
I thought it was fairly well accepted that small deliberate UI delays (for things like loading spinners and animations) can in many cases result in a better user experience. Of course, that would depend on how long this animation is that you're talking about.