I don't know how much it being open-source will help though. The open-source world is chock full of libraries and tools that have been abandoned long ago, despite having numerous contributors listed on the project. I'd say that about 30-40% of Rails gems I come across everyday have not been updated in a year if not more. Sure, they have forks, but unlike the original gem, they are not mature enough to be used in a production environment.

Can I ask a really silly question? Why do updates matter unless there are either serious bugs or glaring missing features? If a tool is relatively bug-free and has a plugin ecosystem which handles added functionality, why does the state of the core program matter all that much?

The real issue is that of nomenclature. If you are a professional software developer (ST target audience) then you are careful about how you use a #1 development tool that calls itself "unstable". It implies certain things about whether it is a good idea to install on a mission-critical server for example, or whether it is a good idea to invest time in writing plugins against its API.

The product itself may be relatively bug-free, but that is not really the issue. RHEL7Beta was relatively bug-free, but I would not advise you to use it for most purposes.