1. Delight is overblown, in my opinion. I think most of the people truly delighted by fancy animation are just other designers.
2. It's more useful to think about state when deciding when to animate. Could the user have trouble perceiving the change in state that just occurred? If so, then use an animation to help them visualize what happened. I believe this is the primary reason to use an animation - all others are vanity.
I disagree with this, as much as I want it to be true. Just ask an Apple/iPhone user to use an Android phone for a week and then ask them how the experience was, they'll tell you something felt off or janky about it, and a lot of it comes down to really well designed animations on iOS for everything you interact with.
Regular consumers may not use the word delight to describe the user experience, but they do notice it when faced with what is (to them) an inferior experience.
This experience has stopped being the case for quite some time now. Sure, a 60 USD low-end device is no ground for proper comparison with a 1000 dollar one, but androids in a similar category absolutely have similar animations and "niceties". I have actually recently moved from iOS to Android, and I do prefer the latter's visual UX. I will even go as far and say that there are less UI bugs.
(As for "smoothness", sure, apple's SoC game is far above any android manufacturer's, which helps a lot)