One aspect of the first MediaWiki architecture summit that I really liked but has been mostly lost, was inviting non-Wikimedia mediawiki users. They're a group that has use-cases that we don't often hear about, and provide a unique perspectives. Although I suppose its not surprising that their involvement has kind of been lost. I would love to see them come back, although I'm not exactly holding my breath for that.
As a non-wikimedia mediawiki developer, who attended this year's summit for the first time, I thought there was a reasonable amount of discussion that would be interesting for users/editors.
There was a lot of discussion about how developers decide what to implement. Community tech wishlist most prominently, but also for other features. I remember a pretty great discussion on the first day around the various ways to support lower-bandwidth and mobile users. There was also a great discussion about the future of mediawiki core as a standalone product. Maybe that was only interesting to me :)
I'd like to see this event keep its developer focus. But I think users/editors can benefit from meeting developers as much as developers can benefit from meeting developers.
Even though many talks are implementation focused, I think users can help make sure the initial use cases and requirements don't get lost in those discussions, and can help with usability and acceptance testing for new features.