This!
Instead of discussing what features are missing, it should be discussed what features should be dumped (from the core)! Now, having said that, this is from yours and mine point of view, people using NC for free. From NC GmbH point of view, the opposite is much more interesting. Brainstorming is expensive; getting it for free from NC users is invaluable…
When CERN started their MAlt (Microsoft Alternatives) project, they had this warning on their page: make sure you don’t fall in the trap of inferior (open source) copies… BTW, they use a customized version of ownCloud…