I think simple is the wrong word. CSS is flexible but it's also predictable (aside from browser issues). It's powerful but it's also just a text file. It has a learning curve, but once you know it, you can bang out a basic CSS file in minutes. I'm sure some of this applies to Office styles, but there's so much more too them. There's all these dialog boxes and sometimes stuff jumps around when you hover over an option, and all the formatting code itself is obscured so if something breaks, it's harder to diagnose what went wrong. There's no simple textual representation of the whole style all in one place. You can't do anything meaningful in Office styles by typing two lines of text, but you can in CSS. To me, that gives a feeling of simplicity, or perhaps lightness or understandability is a better word.
Not to mention, CSS files will probably outlive Office styles by quite a few years, so there's a sense of permanence which I also find comforting.
Danielstraight and NathanKP / please contact me in the email on my profile (I looked for one in yours) I would like to talk to you about how you learned CSS and what frame work your using or tools to Pump out CSS... thanks, rb
Not to mention, CSS files will probably outlive Office styles by quite a few years, so there's a sense of permanence which I also find comforting.