At the core, it might be the same thing as with the outrage over Twitter changing the star icon ("favorite") to a heart icon ("like"). These changes remind people that they're not really in control of the product they're using, they're bound by the decisions of an enterprise who's only acting in their interest if these happen to align with the enterprise's own interests.
But, seriously, it comes with the territory. Some people are okay with it. Some people are not. Both are fine. I don't really understand why it gets so far up people's noses either way.