This seems unlikely to ever be added as visible to non-administrators.
The freedom of individual users to choose how they want to consume the forum is important, and giving special consideration to Watching a topic by making the number visible to everyone is likely to create bad behavior patterns. (Number Go Up Syndrome is very powerful.)
You should be able to take a Data Explorer query that gets this data and mark it as runnable by moderators or employees, if that’s who the requests are coming from.