The question then would be how long does each circumnavigation take?
If a player ends up sitting there for 5 mins waiting for probes to return or even longer in your alternative method people just aren't going to want to sit there that long - especially as they could of taken 5 mins or even half an hour to fly to a planet (or even longer if the planet is really far out).
That could add up to a really long time of players not doing any thing at all.
As it stands i bet they could of mapped that planet in a minute or two if they weren't explaining it
As they speed around in Supercruise they did take like 20 seconds in the livestream
when hitting the backside of the planet. Double that time and be done with it
for normal probes and the backup scan.
Remember, you can have up to three or 4 probes via engineering
up simultaneously.