If there's one thing that should be clear by now, it's that normal users and advanced users don't want to use web-based UIs!
Wrong. I am an advanced user an I *love* the UI of google spreadsheets. Sure, I'm not a fan of web-based apps in general, and a lot of the usual drawbacks apply here too, but man, the UI is so much better that I don't care that it wastes so much RAM and is slow as hell. It's still a pleasure to work with, which I could never say about Excel or OO Calc.