I've noticed the same thing, @bozz. Engagement for me was great here at first but has steadily declined. In my nearly four years of doing this I've discovered engagement is generally fueled by one of two things: 1) excitement over the platform, or 2) earning potential (during spikes in the currency).
Someone dropped some stats into the comments section of one of my posts about a week ago and said there were only about 10K active Hive users. If that figure is true, we need to grow the user-base. I think we need some kind of referral program where people get a certain amount of Hive for each person they bring onto the platform. Not everyone who joins will become active but a percentage of them will. There's a mass migration away from Facebook atm and I think platforms like Hive are really missing out if they don't take advantage of people looking for a new platform.
Also, I wonder if communities could be part of the issue? Those who primarily post in communities instead of using common tags may not be getting as many sets of eyes on their posts.
That is very interesting! I agree with you on communities. They are great for bringing like minded individuals together, but they do tend to "hide" content. 15k is pretty sad. We definitely need to work on that.