Real admins use the best tool for the job, anyway. "Polyglot persistence" is where it's at: You keep your sessions in Redis, you keep your news feed in MongoDB, and you keep your credit card details in Postgres.
There needs to be a threshold of utility before you add an additional data store to your application.
Just because you want to use some unstructured data (which was your original example) doesn't mean you need a new data store that's optimally suited to that. You can store documents just great in an SQL database or in the filesystem.
This is the important bit. Just about every company or web app will have a bunch of relational data and therefore an SQL database of some kind. And storing key-value pairs in an SQL database is really not that hard or inconvenient or slow or whatever - it's gonna be 'good enough' for just about everyone. Why bother supporting an entire extra dedicated KV store when the SQL DB I already have will work just fine?
And lots of NoSQL databases do have these kinds of value-add features. For example, FourSquare writes data into Mongo (and Postgres, as well, actually...) because it has location features built into it.
This is a false dichotomy.