For what it's worth, that bit of the policy was written early in the life of the App Store, when there really was a glut of low-effort novelty apps, particularly in the categories they mentioned, and when app discovery features in the store were more limited. It's probably not as necessary nowadays, but it does help guide developers away from writing apps which users are unlikely to find useful. (And if you've genuinely put in the effort to create something novel, it shouldn't be difficult to convince the reviewer of that - App Store review is a two-way street.)