Big Corp doesn't want its trade secrets on Google's servers, and phones don't have enough interface real estate to contain the full functionality. They work best as satellite devices, in my experience.
As a user in a mixed MS Office + Google Apps + LibreOffice environment, Google's recent work with QuickOffice has been EXTREMELY helpful. My big gripe isn't Excel so much, either, but people who refuse to abandon PowerPoint when all they need to do is create a bullet list.
