@JoshRoss: With this reasoning you may tell Microsoft to not bother making Excel for WP, ExcelViewer for WP would have been good enough.
Yep. If you honestly believe you are going to create anything of value in excel on a phone, you are arguing an extreme edge case. You should count your lucky stars that you can painfully update generic xlsx files that don't have the above listed limitations.
But wait, we might as well just export the file as PDF and view it on a Windows Phone. In that case I could have uninstalled Office for WP and save a few GB of storage. Just install PDF viewer for WP which is 4MB in size would be enough.
That's just more silly extremism, but if you'd rather lose any excel functionality at all simply because you can't manipulate fields that contain macros, be my guest.
It's a security hole, it's prohibitively difficult to implement, and it's an edge case that only serves to perpetuate poor application design choices. If you are writing LOB applications in excel, you are a hack.