Based on our experience in Talk:Content_translation, I was expecting that those conversations that we closed and summarised were shown collapsed by default since the summary already provides an overview of the topic. I don't know if this is also a valid assumptions for other use cases, or if it has been considered already.
Topic on Talk:Structured Discussions
We're still tinkering with moderation actions. Closed really meant Locked, in that you can't add replies, so we renamed it and took out the default collapse. If a topic is spurious, you can hide it, which takes it off the Flow board (but still in the history). That leaves the use case "Reduce the default visibility of a topic to its summary".
+1. The whole point of closing a topic is to reduce its visibility and avoid distracting people, I'd have thought. :-)
We do need both options, and will get them eventually. I.e. We need to be able to use equivalents of both en:Template:Archive top and en:Template:Hidden archive top.
But generally (at Enwiki) we don't collapse closed/resolved topics, except for very offtopic/distracting, or very flame-filled threads.
I made some notes on 6 of the related templates, at https://trello.com/c/x8lHHkA6/
Eh. We sort-of do; look at e.g. AfD where we both "archive" the discussion with a big blue box of static-ness, and then hide it by moving it to another "archive" page where no-one will find it.