You're missing the point which is: when Google was funded, it wasn't Google, the king of search, as we know it today, but yet another search engine in a saturated market, started by 2 academics with no business background.
The reason they were founded was that they convinced the investors that their plans and ambitions go beyond what they've built so far.
It's a remarkable lack of imagination to not see a potential in a good, collaborative web editor. Sure, if they don't ever write a single line of code, it's not going to be anything special. But they probably will and they probably have many ideas on how to move this project forward.
An obvious evolution would be to turn it into a web-based IDE, competing with the likes of cloud9.
Or they could make it an embeddable editor widget usable by others (it's surprisingly difficult to build a decent web-based editor and a lot of web-based software (a forum, a commenting system, q/a sites) needs a good editor).
Or many, many other possibilities. Stop thinking of it as a finished product. Think of it as a first step in a thousand-step journey and try to imagine what the other 999 steps could be.