I also agree. We need missions to place a waypoint in the planet's coordinates. And we should also be able to bookmark custom coordinates from the system map navigator.
Also, i'll take the chance to speak about uss randomness. I think it's horrible. Space is big, really big. The distance between planets and stars inside one system is BIG. How the hell would a pilot find anything there just by chance? I think the point of uss appearing out of nowhere when in cruiser mode is just anti-space-simulator-wise.
So, i'll give my suggestion about it, though I think the devs won't care, because the game is pretty much finished already.
When in cruiser mode, other ships would only be visible at a short distance- depending on sensors range.
We would have a ping scan, that would search a wide area in front of the ship (45degrees radius max). this scan could mark on the radar areas where some type of materials or emissions were detected. ( like the radar of the srvs)
The closer the distance, the more defined would be the area (smaller, brighter, until the uss was located)
These uss would be created when the player entered the system, so they would be half-persistent, and force the player to search around. Not stay in low speed and wait for it to appear)
Other ships in supercruise would appear too, with temporary location, and pinging ships would appear in other ship's radar. So it would be like a game of blindmen touching around to find each other, until they are at close distance.
I think this mechanic would make it much more fun to explore, and even hunt other ships.
Oh, and special radar dots would appear when pinging mission related ships (pirate hunting or assassination, etc...)
Cheers.