[...] Perhaps people who get most of their news from this mailing list are [...]
Why does this matter? What other sources are there?
It seems you're saying there is a divide between the main development community (on this list) and some other unspecified group which communicates by some other unspecified means. If so, what you need is not a dictator or an architect or a process, it's a reunification.
Whoever has knowledge of such a divide can help with simple steps, in particular by publishing a "map" outlining this divide on a mediawiki.org page.
[...] the vast majority of the WMF staff developers, even if they were unpopular here on this list? Given our staff/not ratio [...]
See above.
[...] It could be that the general pessimism about the direction of MediaWiki (or lack thereof) is not shared out here. [...]
See above.
have their own ideas about what things should be priorities, but have no expectation that those ideas will be considered for resourcing.
The solution here seems rather straightforward, if not simple: ensure the architecture committee actually feels empowered. The WMF could promise to not invest resources on something that the committee officially declared a bad idea, for instance.
Nemo