Most lay users likely won't be able to understand the discussions that take place on wikitech-l. Hell most lay users don't even know it exists.
Lay users don't write templates either. People who write templates are wizards. Templates make my eyes bleed and my mind hurt, and I've been developing for quite a long time.
While I won't weigh in on whether or not the choice of Lua was our decision to make or not, I don't think that the argument that editors should join wikitech-l is a good one.
I don't think the editor community has much reason to participate. The template creator community does. They are more than technical to understand things on wikitech-l.
Perhaps the ambassadors mailing list? But wikitech-l? No.
I am curious though to see if we ever even mentioned this idea to the editors on at least enwiki though. I think such knowledge would greatly help everyone else here in evaluating whether or not we included the community enough on this decision.
The "community" is not a single thing. The community is made up of hundreds of sub-communities. If people are interested in technical decisions, they need to participate where technical decisions are made.
- Ryan