[spion]

Has anyone considered that maybe MongoDB attracts developers because its extremely easy to use?

Consider their great homepage scenario:

  - click "try it out" 
  - type "tutorial"

Couple of minutes later you know enough MongoDB for most CRUD apps.

Or the restriction-less API:

  - collections simply come into being.
  - store arbitrary objects without schemas
  - create arbitrary indexes
  - search by arbitrary conditions

I can't imagine how one would go with lowering the barrier of entry even further...

Yes, this is mostly marketing and usability. No, you can't skip on those and rely only on technical superiority - you have to fight on all fronts.