Docker support is a new feature to enable more complex jobs where you need to control the entire stack, for instance, maybe you need imagemagick installed on the core machine, or ghostscript. IronWorker can support that. It also allows you to test your workers locally before uploading: http://blog.iron.io/2015/03/the-new-ironworker-development-w....

That said, you don't need to think about Docker if you don't want to and an IronWorker can be a few lines of code too, for example:

https://github.com/iron-io/dockerworker/blob/master/ruby/hel...

Or node: https://github.com/iron-io/dockerworker/blob/master/node/hel...