In the end, neither the ADS nor the FSS solved (or even improved upon) the original problem: having nothing to do while exploring, besides sightseeing. have you all wondered that, with 4 billion systems, who knows how many billions of planets, almost 4 years after Horizons launched, there is still not a single reason (from a exploration gameplay perspective) to even land on a planet?
Neither system solves the actual issue, that after the initial step, seeing what planets are there, there is still absolutely nothing to do, only a miniscule amount of things to find, and very little if anything at all to interact with.
With the ADS, you opened the door, and could look inside but do and touch nothing. The FSS just added lockpicking to open the door, so you then could look inside but still do and touch nothing. This is why is might feel satisfying, a step forward or an improvement to people who are into the "lockpicking" on it's own, but feel like just a pointless chore and an actual step backwards to people whose interest was to finally be able to properly explore the house, open the closets and the drawers, investigate the basement, etc.
I personally couldn't give a rat's arx if a particular ice ball is more to the left or more to the right. What I wanted was to have compelling reasons to investigate that ice ball, land of the ice ball, investigate signals in the ice ball, perhaps find something on the iceball, bring stuff for science from that iceball. Locating the iceballs to me is merely a starting point, not the end all. I might be able to put up with the FSS if then it enabled potential hours of gameplay in the system, but never as an end in itself.