The thing is, it's not just a grid with some cells that does some math. Excel is incredibly powerful and if you integrate it with the full Office Suite + Sharepoint, you can really start to do some amazing things. I'm constantly blown away with the tips and tricks I learn from people at work.

I recognize that most startups aren't going for the full MS package (esp. Sharepoint), but I look at these tools as a suite that grows in power as you need it. With the Ribbon, you get great discoverability of these advanced functions as your needs arise.