It makes me wonder if Google has become so "good enough" that more and more engineering effort will be spent for smaller and smaller returns.
It isn't that the special effect doesn't have an impact, but that you don't specifically notice the effect because it blends seamlessly into the rest of the film.
Okay, I guess it depends what you mean by "notice." I certainly was aware that much of Titanic was shot in front of a green screen. No matter how photorealistic special effects become, it's often fairly obvious what's real and what's not.
Unfortunately the opposite example can be found in the same product, Gmail; when they visibly and ostensibly changed the UI, it was immediately noticed, and widely hated.
* There are a ton more people actively researching ways to reverse-engineer and game the system.
* There are a ton more sites and more content getting generated, including bot-generated ones which are of dubious quality.
How do you know it was the "biggest overhaul"? Google is known to use every moment to hype itself.
Also Google has been doing these changes since 2011 almost monthly. Now sites that sell things or make money have almost given up on "free" traffic from Google, they know it's pay to play (outside Product Search it's not openly pay-to-play but you get the message after a few 70% traffic reducing updates).