I think the point of the criticism I read was that the edit should have worked. There is no reason why the opaque mess following what was obviously a definition of the contents of the spreadsheet should even be there let alone be dependent on the original contents of the cells.
The obvious reason to have other stuff depend on the value of the cell would be to store a cache alongside the formulae. In a 300MiB XSLX, you don't want to evaluate every formula every time the spreadsheet is opened.
If caches have a place in a file storage format, they should at least be optional and separate from mandatory content, and I got the impression from the critique that they were neither.
