They can't nerf exploration missions, because they haven't implemented any exploration missions yet. Hopefully someday.
As for Dyson Spheres and anomalies, we really need better exploration mechanics first before they go adding exotic stuff like that into the game. Geysers, fumeroles, fungal life, and alien ruins have all truly showcased the dire need for better exploration mechanics. Without those first, any new content will be relegated to the very small group of tireless devout diehards who can spend dozens of hours searching with only their eyes, or possibly using quirks of the game engine to measure asset load times for hunting again. Hardly ideal from a gameplay perspective, and certainly not good game design, as it prevents most of the playerbase from participating in exploration at all.
Build the foundation first, then start framing the house, painting the walls, and decorating the rooms. When you buy a living room set before the foundation is ever finished, then that furniture simply goes to waste rotting out in the weather where no one wants to use it. Like the OP says, a half finished foundation without a house on it just sucks.
I'm not a programmer but I have to think there is low hanging fruit that could easily be added, that would make exploration more fun. Yes, continuing to work on the foundation of the game would be great...but how about some weird easily added stuff scattered all throughout the black, to make things more interesting, while they do the more complex stuff over time?
Wouldn't it be cool to be scanning an earth planet, and strangely it looks like it has the ruins of a city in it...when suddenly a new contact appears...oh crap it's a crystalline entity and it wants to eat me!!! In a nebula you see a signal source and it's an alien city-ship, long derelict, with a relic worth 100 million credits. Wormhole discovered, worth 20 million credits, but that is 200 million if it's stable...so you travel through it, and the other side is NOT STABLE, now you are stuck 40k light years from home and are a voyager making your way home.
IDK seems this stuff wouldn't be overly hard to implement. But maybe it is, idk.