What exactly do you want back - the xDS functionality as it was pre 3.3 or your description of only placing bodies on the system map?
Exactly that. Body placement. See Marx's post within this thread. He goes to a great length to explain the motivation behind this request. Pardon me that i won't supply You for now with the post number.
You can. Run the FSS and populate the system map.
Look, again. I don't dislike FSS. Let's start off with that. It's a great tool and the closest we've come to an actual "mechanic" in terms of exploration.
You sure can do anything You could back with ADS in place.
The thing is, again, as described many times, that for one there is additional time investment into doing something many don't find appealing / immersive / fun by force.
For those who like cherry picking and going hunting for ELWs FSS is a great tool. You can see what's in the system right from the get-go. Not to mention being able to scan it from the entry point.
Why would one like to have map revealed? Allow me to explain. Back in the pre 3.3 time certain players found out that they are dissatisfied with seeing the same configurations over and over again. See one glowing gas giants see them all. What else remained mouthwatering in the game? Configurations. Seeing bodies in extraordinary orbits. Maybe there are moon in close orbits with eachother, a star and gas giant at that? All close to to the main star. Maybe black hole orbited by white dwarf in "close" proximity. You never know what Stellar Forge comes up with. So those players went seeking just that. Jump into the system. Honk. Is the system worth staying in? No? On to the next one. All done while scooping and then charging the FSD. Covering far greater distances than they can do now. And as You may have guessed, seeking to find these systems is no easy feat. Since the genertion is to a degree random and there are 400 billion star systems to see. We'll never get to see it all. Now this group of players is forced to scan every system whether it's interesting or not. So as You may imagine too this cumulative time results in greater levels of dissatisfaction. Not everyone is keen on finding ELWs and being enthusiastic about being the first to do so. Everyone can play differently with different goals in mind.
Another group of players played by certain set of self imposed rules. People would go on tagging only the systems they found interesing using all or nothing method. Now to see what's in the system they are obliged to have it tagged(no, self destruct is not an option).
I may have misjudged You based on Your style of writing. Maybe You are more eccentric than salty. Who knows. It's easy to aim and fire words at one another through internet.