I think they're placed and sized based on frequency of use.

Anyone who thinks file -> print -> page setup is a better place for orientation buttons than the ribbon gets my curmudgeon award.

That is a pretty good place to have orientation buttons for printing. Especially if it's in the exact same place in practically every program that can print. Programs like Word managed to have toolbars for all kinds of things before the Ribbon interface, and that was usually fine. Often they even had printing-related buttons (in addition to file -> print).

One big difference is that these tended to be more compact and one-dimensional. There's a lot of eye movement involved in scanning a ribbon toolbar, looking for something, since you have to scan both up-and-down and side-to-side; and the mixed-size icons, mixed icons-and-labels that don't segregate icons and labels to their own rows or columns but jumble them together so you're always scanning a mix of both, and inconsistent placement between programs make the whole thing feel slow and frustrating.

> I go looking in the top "file - edit - view - [...]" menus for things that used to be there, find them absent, and then have to go play Where's Waldo in the damn ribbon.

My experience in Word improved dramatically the day I learned the Alt-Q shortcut for just asking for what I want instead of combing through endless menus.

I switch between Mac and Windows often enough that this would be pretty frustrating, however I'm glad it's there.