I think it's a balancing act. I don't want "X marks the spot", but I also don't want fruitless searching of every inch of the planet-that is opposite ends of the "just not fun" scale.
Instead, I want our scanners, when used actively (not passively), to narrow down our searches to fairly strictly delineated Zones-most likely colour coded on our planetary maps, & with the centre of the zone clearly indicated on the planet's surface whilst we're flying towards it.
For many findable things I agree a Search Zone might be acceptable.
But better to have a variety of scanning modules available, that if stacked properly in an exploration ship would allow one to start with a broad search and quickly narrow it down. Each of these would, of course, have nice audio and visual effects.
Thinking about large settlements on airless worlds, they are bookmarked for us but they could just as easily show up as massive IR and EM signatures on an otherwise blank sphere. Easy to spot from orbit, no messy searching needed, the sensors would show exactly where it is.
Similarly, if we think immersion, realism (consistent game logic), we have Nav Beacons and Wing Beacons. Once a player finds something like the first Barnacles on Merope 5 C, they should be able to put a beacon on it that will show up on sensors once in orbit. It is really dumb to be searching for random forum and internet posts of LAT/LONG coordinates to find sites like that and then to have to fly in circles to get the general direction just so, etc.
Once we have planets with atmospheres that can play havoc on sensors, and Earth-likes where the EM radiation would just be a blanket, the ability to find specific POI via other means like a beacon could become even more important.
Downed ships should have flight recorders that are sending out beacon signals that make their general proximity relatively easy to find once in Orbital Cruise, lets say.
I spend so much time just going from A to B in ED, to think players should fly over planets searching for stuff that can barely be seen at 1-2 km distances is insane.
I am really surprised players have found any of the special POI sites in the game through anything but sheer luck or coincidence. Kudos to those that found these when they were actually dedicated to looking.
I don't like the current POI "follow the spinning circles" game. Although better than nothing, it seems like totally random behavior and to me when looking for things like downed pilots and data recorders, just makes little sense. Fusion engines if that is what ED is based upon, would also become highly radioactive and so crashed ships would have a chance to become beacons if their containment systems are breached.
Lots of ways to play it. Of course, some things may just be hard to find and that is what it is for a Simulation-lite game like ED. Barnacles first discovery, sorry, just gonna be that eyeball MkI work. But for a game, it does seem a bit daft to me unless the stuff is as an Easter Egg.