I think we've got enough features down for the current iteration of the plugin. For every feature we have there are a bunch of people who want us to implement a number of new things. As you can see on the feature suggestion system there are literally hundreds of things people want us to work on. We have only a few developers, as well as a couple of major projects currently in-progress. Time is by far our most limited resource. Everyone argues that their suggestion is the most important thing to work on, but that doesn't mean there are more hours in a day. This is one of the reasons we added in a voting system, since it can help inform our priorities (although it does not dictate it).
I don't see why other third-party addons need to modify the official addon at all. Can't you just add separate actions and expressions to use new features?