As long as it has the “remain pinned until unpinned by you” message I think it’s important to have that show. Else members are more likely to not be aware of the fact that they can unpin a topic and that could cause them some annoyance.
To me, it’s not any less important as showing other “staff action” posts to clue members in to what state a topic is in.
True, the “now closed” “now open” and ilk cancel each other out and so they become moot.
Deleting those “automagically” might be more work coding in than it’s worth and as long as they can be deleted it isn’t that much of a concern IMHO