MS had the best thing in the world on its side: 10 years of users being trained in their product and nobody else's. So what do they do? Change it completely! Brilliant! I can't count the times I've been in a meeting going over a document with someone using Office 2007 and them saying "Umm, I can't find the Bold button anymore" and sitting there while we go through multiple menus to figure out that what used to be a single click is now three or four (after you figure out how to do it). A room full of people .... looking for a button ... that used to be on the main tool bar. How much did that cost?
Probably a helluva lot more than folks learning how to use the keyboard for commands rather than searching menus for buttons to click. Highlight your text to be formatted. Ctrl + B for bold. Ctrl + I to italicize highlighted text. Ctrl + U to underline. I'm in the IT industry and you wouldn't believe the folks who actually use the mouse to cut and paste text (rather than use Ctrl + X, C, V).