So you are taking a mechanic you don't like and making it worse? You want to spend more time doing something you hate? I can't help thinking that you don't have the right solution there. If you think that the FSS gives too much information, then just take some information out of it. We've said on here that we'd be happy if the count of POIs was removed. You could remove detection of them as well, although you might get arguments.
But to be fair, it doesn't give all information and all rewards. You still need to travel in order to map. If I understand correctly, you didn't need to do that with the ADS and you didn't need to spend as much time as close to the planet in order to scan it. So it's now more work and takes longer than it used to. Which is what you want.
The DSS needs to stop permanently turning planets blue for a start.
Neither the FSS or the DSS are meaningless mechanics. For instance the FSS is a narrow-beam, phased-array radio telescope with a Fourier transform and a coaxial optical telescope with a spectrum analyser. You could build one now, except it might be the size of a few football fields. It makes perfect sense.
Personally I'd find the argument that you still have to fly to planets to map them would carry more weight if it actually resulted in a MAP.
'Mapping' a non-landable planet performs no function other than credits and potentially a tag. There is no additional information gleaned, no meaningful 'state change', so for me it is nothing but a time-sink.
'Mapping' a landable planet without POIs likewise does nothing.
So that leaves us with 'mapping' a landable planet with POIs. The mechanic for locating POIs is simplistic and because it results in exact coordinates, it becomes an exercise in sightseeing. This would be tolerable if you knew in advance what you were going to find, or if there was any meaningful difference between them. However, since they're all cookie-cutter objects to scan and then shoot bits off, I found all motivation disappearing around my fifth planet.
Finally, as always when people try to justify using terrestrial astronomy techniques, I'll point out that we're flying FTL spaceships which can get up close and personal with planets in seconds, so why on earth are we messing around with telescopes when we can simply fly there?