If people use your product all day, everyday, and you release the biggest overhaul of your product in 4 years, and nobody notices, is that a good thing, or a bad thing?
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).