I have checked out Quickbase, Airtable, Ragic, etc.
What I've noticed is that I always want the ability to go to code when I need to. My clients are all on Rails apps today, and I'm happy with rails as a dev solution. And, I don't want to give up that flexibility.
However, there are use cases where I want to just use a form builder UI to manage a data model. I've been using http://form.io for that recently. You use a form builder to generate a UI and an API simultaneously and submissions are stored in Mongo. And, I can build the app as I want using their API.
I think that paradigm is the future, it just needs more refinement.