... but that bubble keeps people like you reading all the topics
Haha! Well, not really, though.
That bubble is effectively a subscription to the entire forum -- every topic is being treated as a subscribed topic or email. Especially for a large and diverse forum, that's crazy: you're asking people to either deal with this red alert bubble, or to constantly make sure that every single topic is read, or at least "marked as read".
So, I do still want notifications that are relevant to me -- when somebody quotes me, for example, or when I actively choose to subscribe to a thread of interest. But I don't want two notification centers with the expectation that I need to have the entire forum marked unread.
Most forums I've seen have different forum markers/class names applied to categories with no new/unread posts. I know nodeBB is trying to do things different, but that seems like a very sensible way of handling it.
Perhaps this is just a styling issue, though. Graying it out does wonders and makes the number a bit of background information, rather than a BIG RED ALERT. ex:
You could even slap a display:none on there and disappear the bubble entirely. I'm sure there's enough on the development plate, so perhaps leaving it in the theming realm is appropriate. Though it does seem odd to have to resort to that.