Trust me I used to be one of those people who would say the same thing you're saying. I was like "What's the big deal? These people just don't like change. They'll get used to it."
Except that you don't anymore.
The reason I hate these changes is because things just don't work smoothly and disrupt your workflow, not to mention the UI being messy design-wise (I have NEVER complained about Apple's design changes ever since the first iPhone).
And this is all because of the new features they introduced they're trying to shove down user's throats. Most of these features are built to satisfy Apple's agenda instead of making it easier for users to use. Just read what others have already said, these are features built for Apple, not for users.