Generic containers are an awkward mid-way point between special-purpose containers (a Wordpress instance or a rails app on heroku) and an actual machine.
You get the hassle of maintaining your own instances, without the flexibility or well-defined performance characteristics of an actual box.
The market you don't see is the market for PaaSes, which make the question of "how do I run this, anyway?" basically vanish.
Continers are the fundamental building block for modern PaaS design. There's a reason OpenShift 3 was built on top of Kubernetes, or why Cloud Foundry was built on top of a pre-Docker container system.
The one thing I can say for Docker is that before it launched, it seemed most companies using container technology were not that open about it. Docker appears to be the company that spoke about the unspeakable and caused lots of software to suddenly be developed in the open where it was all behind the scenes previously. Maybe I was just clueless, but the more Docker pushed their releases, the more other companies suddenly had all this code to release.
I think Docker deserves pretty much all the credit for making containers a mainstream concept. In particular, they tied it together the existing primitives into a uniform concept with a developer-friendly interface.
The very fact we call them "containers" is due to the analogy Docker made to shipping containers.
Well there you go. I remember them being almost exclusively referred to as Solaris Zones, but some Googling shows that Solaris Containers was used interchangeably as early as 2005. You're right.
However, Docker did deliberately make the shipping container analogy -- the name, the logo and the early blogposts all consciously focused on the similarity with the invention of shipping containers. So I was half-right.
You get the hassle of maintaining your own instances, without the flexibility or well-defined performance characteristics of an actual box.
I just don't see the market.