Submit a more complex application with features you can disable server side after review. While Apple doesn't approve of easter eggs they can't see during review, I've never heard of them noticing (let alone complaining about) features disabled after review.

You should also carefully consider why you don't support email and MMS. You should allow your customers to to say "Text Pictures to 12345 or email them to [email protected]"

Downloading an app is unlikely to be easier than using the native sharing features for most users, so keep that in mind if you really care about simplicity and ease of use.