I don’t know about Wikimedia being super cautious when adopting technologies... I host a MediaWiki instance and there’s been a lot of “not so cautious” tech decisions in the past. Jumping early on the HHVM train (which they eventually had to leave); adopting Lua for wiki modules; developing Parsoid as a Node service (now rewritten in PHP)... None of these was the “safe option”; in some cases it worked out well but in others it didn’t.
None of that was forced on anyone, though. Everything you mention are purely optional components. I think it makes sense for them to explore new technologies like that while still keeping their general requirements conservative.
Yeah, but those components were heavily used on Wikipedia and other Wikipedia websites, and some - especially Lua modules - are fundamental once the wiki grows to a certain size, since wikicode templates are quite limited and suffer from performance problems.
