Somebody out there has demanded that he / she have both the ADS and the FSS.
Demanded? Most of the
demanding is coming from those who like the FSS and are demanding that nothing be changed, or demanding that if something is changed it be done with additional penalties inflicted.
The FSS is most importantly a tool that will allow players to find stuff that FD have, or are planning on putting out there. That's why it's installed in every ship, because they are hoping to introduce game-play that will require it to have a decent chance of being found and they want all players to have it.
My own preference is to have a choice of 'tools' to use to play the game. Just as I do with ships, weapons, careers - in fact pretty much everything, including who I choose play with.
The main reason that an ADS that populates the system map should be optional is that some of the people loving the FSS still use the system map to periodically check on their progress, and I see no reason to spoil their experience by making such a system map reveal mandatory.
Since the FSS gives all the information that the ADS did after it is activated, why does it matter what view that information is given in?
I would say, and have already, that a player should not be able to target something from the system map then open the FSS and have that object targeted, but so long as they are happy to use the FSS as it is designed, to
first locate and then scan something using just the FSS interface, then why should they not have that option?