I've seen more spreadsheets than I would care to admit, and what drives me crazy about each and everyone is that it is not readily apparent where the work is being done. I think you could say the same about a "programming language" except that the programming language is usually not also the product. When the interface is the code and the output, the lack of consistent implementation is something I find frustrating.
It's a nice thought experiment, but in my mind I think the world would be a better place without excel.