That's funny because, again, I'm not talking about wanting support for VBA on the phone. I'm talking about blocking VBA but allowing the spreadsheet to be edited. You are oversimplifying why Microsoft shouldn't work on this feature by making it out to be a much broader scope that the issue presented.
Every feature has to be written and tested before it can be released. If VBA-enabled documents were disabled but the document editable, that means that WP needs to be able to save documents with VBA macros in, otherwise you end up with customers complaining that when they get sent a document, they fill it out and email it back, all of the macros are missing.
Disabling editing when there is stuff in the document you're not sure you can preserve over an edit is less work than enabling edits and potentially corrupting the file or throwing away information in the document that customers might really want.