Questions:
1. Why is my iTunes icon in my dock now red? Did Apple change it from blue to red? If so, why? Can I get the blue icon back? The red one makes me think something is wrong that I need to fix
Answer: They've changed the icon in iOS to red and now they did the same think to the icon in OS X. It's ugly. And yes you can change any icon you like. Just use google and you'll find changing icons on the mac explained many time.
2. What happened to the navigation side bar that showed all my play lists? Can I get it back?
Answer: just press the playlists button in the middle of the white top bar and your side bar will show.
3. Where did the cool cover browser go to? Can I get it back?
Answer: Gone since iTunes 11. No, we won't get it back.
4. Rhetorical question: Why does Apple, and every other software company mess up a product that doesn't need fixing? Why make me re-learn how to use a product with every friggin' release and upgrade? Sheesh! It was working fine. I liked it! Don't make me have to GO BACK TO SCHOOL and waste time to learn how to do stuff that I already knew how to do. The point of a program is to use it to DO STUFF! The point of a program should not be to "show how cool I can be because I'm a software wizard!
Rhetorical Answer: I tend to agree, and I tend to disagree. The ultimate rule for engineers is "don't fix what isn't broken". If you do that anyway people will see this as "change just for the sake of change". That's annoying and produces unnecessary learning-curves. So that's where we agree.
One of the effects of the present change is that a part of the sidebar has moved to the upper white bar, as shown in the picture below:
The result is I don't have to scroll down to my playlists in the sidebar anymore if I want to add or change anything in those playlists. The playlist are always right next to the library-screen. That's improvement and not "change for the sake of change".
On the right of the white top bar iTunes 12 presents al selection-option in one menu right in the main screen. You don't have to go to the menu at the top of you desktop to make your choices for columns and filters. That's good, that is, if it would work properly. Selecting columns is not working properly yet IMHO. If you add or deselect one column the menu will be closed right away. In iTunes 11 you could add and deselect multiple columns at once. It would close when you were done. That makes more sense. If they fix that, the new way is improvement and not "change for the sake of change". So on those part I disagree with you.