I did think about licensing. There are two big problems with that:
1) The costs of running a single instance of the application far exceed the plans I was selling. It requires a certain amount of amortization to become cost effective for a lot of people. Dealing with Windows and Mac licensing and the hardware required just to get the browsers going, let alone the analysis engine, is too much for most of our customers.
2) Browser vendors pump out releases every 6 weeks. Without some form of ongoing support, the app would become obsoleted in fairly short order.
As such, the licensing model only makes sense for those that are comfortable messing around with the source. While the article makes it sound like it's a coupled nightmare, most things are actually laid out very nicely. But, it's still a level of complexity a lot of people aren't going to want to tackle.