I've yet to see a good Wysiwyg table editor on the web, especially open source and embeddable. So if you can deliver on that at some point, that would be a big reason for me on why start using. I like minimalistic approaches, but so far the minimalistic approach is usually to just forget about tables, which I don't find acceptable. Emacs Orgmode so far has the cleanest simple approach to this and I'd love to see that replicated.