This finally gives the committee a clear place in the "chain of command", and real authority over software development at the WMF, where it formerly had none.
This is a compelling argument, but why not call it Wikimedia Foundation Technical Committee then? It would also be easier to clarify that it's mostly/only meant for WMF staff and whoever else decides to submit to its process (this is already implied by phrases such as "developers or teams"), rather than for MediaWiki in general.
I think it's appropriate for the WMF to have some body to take care of technology beyond MediaWiki, think for instance https://meta.wikimedia.org/wiki/FLOSS-Exchange (still missing a contact point since Erik went, btw) and all the cases where disagreements over MediaWiki or Wikimedia practices have been worked around by using non-MediaWiki solutions.
I'm not sure it was necessary to give up on having a MediaWiki body in order to have a Wikimedia Foundation one, but probably two parallel systems would have been confusing. Hopefully at some point after this repurposing we will be able to afford integrating more third parties into the "central" development process and an actual MediaWiki governance will be useful/possible/needed (this was the core idea at the time of the Architecture summit 2014 etc., IMHO).
Ah, https://www.mediawiki.org/wiki/Gerrit/%2B2#Revocation at some point listed the WMF ~CTO and currently contains an unlikely "anyone authorized by Wikimedia Foundation's Board of Trustees". Some updates might be in order.
Nemo
P.s.: Not commenting is not necessarily a choice. For instance, the talk page doesn't use wikitext and therefore creates selection bias for the discussion.