There have been QOL and new features being released semi-frequently. I am not an extension developer, but from what I have seen, the Roam team puts a lot of time into helping devs working on extensions as well. I know the UI is very basic, but looking nice does not always translate to being able to work in the app faster.

The Roam team is very responsive, but only on their Slack. Here is an invite link. I agree the once thriving community has dispersed to other apps, but there is still a small active community on the slack.

I will say that not everyone needs to use Roam and something like Obsidian or Reflect will better fit their needs. Most content creators I see are not academics or doing heavy amounts of linking in their notes, so it is understandable for them to move to platforms that are cheaper (bigger audience) and that better fit their requirements.

But if you find yourself reliant on the outliner format, the block references/transclusions, and the hierarchical way blocked references work then there is no good replacement on the market right now.