Users hate change
"We know what's best for the user" is assuming you are even designing for the user in the first place.<p>The user is often not the customer, and design changes are ultimately here to serve the company, not the user:<p>- How can we increase number of ads users will tolerate?  
- How do we increase the amount of content users share?
- How do we increase the number of likes/hearts they send?<p>I wouldn't be surprised if the lionshare of user backlash comes from decisions that weren't meant to serve the user in the first place.