And a glorified database, and chart making tool, and whatever business app they can hack together.

Right, and that's why it doesn't really matter what innovative things don't get added to Excel because people wouldn't be using them.

Spreadsheets at their core are a visual intetaction model; a table with cells that can affect other cells. Beyond that core, you can do whatever you want - including with Excel, so the 10% that don't want to treated as a calculator can do so with a little bit of bespoke programming.

I've implemented several business applications where Excel was the user agent against specialized backend services. This was before the browser took over the front end in developer's mindset.