You can recognise such things as Earth-Like Worlds and Green Gas Giants without scanning lots of blue blobs.
I've got nothing specifically against that. It's a good solution.
However, it's a good solution only if GGGs are the only sorts of planets that you are looking for. At the moment, they probably are but that isn't necessarily going to remain true. Perhaps fleet carriers require us to scoop gas giants by flying through their clouds. Suddenly GG with life will become great places to visit. Or maybe we find a use for icy bodies with pink streaks.
At the moment I honk while I am fuel scooping and then flash over to the system map to see if there's about the right number of bodies in it. If it looked the same whether it was previously discovered on not, I'd have to look in the individual tags. Added to which I like the surprise of not knowing what I am going to find. A populated system map would give the game away.
If you're looking for an icy body with pink streaks you had to approach it to determine that, even back in the ADS days. The System Map doesn't provide that level of detail, so the FSS has actually improved the search for those, since you don't have to fly to them to find them. GGGs were visible on the System Map, which is why people want the visual information back on initial scan.
Carriers will be fueled by mining, according to FDev. GG scooping is likely to come as part of atmospheric landings - so it's potentially years away.
I definitely wouldn't force the System Map population on anyone who doesn't want it. Just make it an optional module and everyone is happy.