And there it is again: "For any Squiz clients" - it's not open development in any meaningful sense of the term. Make the roadmap visible to all users, so they can see what's likely to be developed. Even making it open for users to view, but only allowing paying clients to make new suggestions or comment would be an improvement on the current situation. That way, people can look at what the system does, and what it's likely to do in the future, and make informed decisions on using it based on those.
Also means that people can see how long a feature has been top idea, and what progress has been made towards it, whether that is none or nearly complete.
Just because Greg mentioned Roadmap is only available for Squiz client, doesn't mean Matrix is not open development. Nic and I have contributed code from our own personal time and they have been accepted into the core Matrix packages (Nic - JS API, Captcha enhancement, MP3 and video assets; myself - File bridge, virus scanning, support script and various bug fixes). There is also the public bug tracker which the Matrix team actively use and keep in sync with Roadmap for any features on Matrix (Also some users have provided patches for various small changes through the public bug tracker as well).
The reason the asset map has not made any progress is because it is such a key feature with a lot of hidden functionality that would have to be replicated to almost 100% before it could released any how (and there are other factors like costs, training, users resisting the change etc).
If you have any contributions you want added to Matrix, we are more than happy to verify and accept them, just we find any user contributions are rare.