Decorative effects are easy to add and easy to forget. Meaningful interactions are harder to design, but they are what people talk about after the launch.
A simple test
Before adding any effect, I ask whether it helps someone understand, decide or remember something. If not, it probably belongs in a lab experiment rather than a client site.
Cost matters
Every effect has a cost in performance, accessibility and maintenance. Removing three decorative animations often pays for one interaction that really matters.
The best interaction on a page is usually the one that makes the next step obvious.