Well, as you point out, it's all subjective opinion, isn't it.
The facts are that the FSS makes tagging systems quicker, makes revealing the existence of POI's possible, removes the need for potentially long SC cruise journeys unless you want to map a body and adds something active where before there was only passive. Whether these 'facts' make it good or bad will depend on what your exploration goals are and perhaps more importantly, whether you enjoy the interface.
That it provides a sense of 'discovery' is more on the subjective side. With 400 billion systems, IMHO dropping into a system to see whether there might be anything of potential interest there was also a sense of discovery, just on a different level - the galactic rather than the system. And if there wasn't anything that I felt piqued my curiosity I could move on to another of the essentially infinite amount of systems available for me to explore.
Those that don't like the FSS are simply asking for FD to consider re-instating an
optional way to explore that doesn't involve having to use the FSS for the majority of their exploration game-play. Nobody is asking for the FSS to be removed or even changed, so honestly not sure why the hostility to that request exists.
Nobody is insisting that you (or anybody who enjoys the FSS) be obliged to have a system map reveal if you don't want it.
(As to the argument that it would take up too much dev time, that's also IMO subjective. Nobody from outside FD know how much time it would take to re-instate something that already existed, and that to an extent exists even now when you FSS a previously discovered system. And 'any dev time is too much dev time' is a pretty poor and selfish argument.)