As an exercise, it's an interesting project. As a product, "better than Google docs" is not getting anyone anything - [Microsoft hatred aside] that space is where Excel lives. And as always, Microsoft is eliminating any of Google's potential advantages systematically.

After nearly 40 years of commercial spreadsheets, the empirical evidence is that spreadsheets are hard, otherwise there would be more of them. And the reason Excel dominates is because they get so many of the non-trivial details right.

Example: consider how often inaccuracy of JavaScript floating point operations makes a blog post appearance on the web [I recall several even on HN] versus the rarity of similar observations regarding Excel calculations. Then consider how many complicated floating point ops are done via Excel functions every minute of every day by non-computer scientists and non-programmers.

A couple of years ago I came to the conclusion that Excel, not Windows, is the killer-app for Microsoft, and that Microsoft knows it and invests in it accordingly. The person who decides on office suites is the manager who uses spreadsheets not the people using the word processor [in which case we would talk about WordPerfect not MS Word as the standard].