In no particular order of importance.
1- More interesting things things to find, both scenery and interactive, in space and on planets. More planetary features (like the geysers and fumaroles).
2- More space and planetary environmental dangers/hazards. Things to watch out for. Gamma ray bursts, extreme radiation, solar flares, solar winds, earthquakes, decent volcanism. Allow explorers to do detailed scans of such (or at least some) environmental hazards at their own risk.
3- Things to find and pickup on planets that are actually worth it to bring back.
4- More things to scan. We are exploring the unknown, traversing alien planets for farts sake. Surely collected data from stuff on alien planets must be worth someting. Ground surveys, mineral analysis, alien vegetation/lifeforms analysis. "Scientific" things to be done with the SRV or with a landed ship, (the ground version of detailed scans), that we can bring and sell to universal cartographics or some new entity like "Xeno Biology and Geology Institute".
5- "First landed on" tags. The ground version of "first discovered by". (not something I personally care much about, but for those who do)
6- Automatically populated list of records. A self-generating list of star and planet records (largest mass, smallest radius, hottest, coldest, etc, like the records section in this
site) that gets populated when the player sells the data to universal cartographics.
7- Better ingame representation of space and especially planetary environmental data. There's a huge nerdy list of numbers about each planet (heat, pressure, gravity, etc etc etc) but none of that is actually
seen nor more importantly
felt in-game, except for gravity. For instance, a freezing cold planet is exactly the same as a scorching hot planet from a gameplay point of view. This is a waste of the Stellar Forge potential (in terms of translating ingame data into actual gameplay). Players can't even notice the difference, without going to the system map and look at the numbers.
8- Better exploration ship UI. Show at least some basic data about the star or planet after finishing the scan, without needing to go to the aforementioned nerdy list screen.
9- More celestial bodies like comets, and black holes that actually pose a threat without a "automatic ship brake". Let players approach them at their own risk. Better black hole visuals, like accretion disks on some.
10 - A couple of new exploration ships. Sick of the lakon console, or having to use the scraps from other professions.
11 - More SRVs, with different handling and capacities.
12 - More detailed planetary scanning mechanics, with increasing detailed results.
13 - Exploration missions, where the player is requested to go investigate and collect detailed data from somewhere, either objects from space, of geological/biological data from the planet soil, or from some space/planetary anomaly, etc.
14 - More Star Trek, less Star Wars! I understand that is far, far more difficult to implement a Star Trekkish game, than to implement a Star Warish game. But nothing really worth it was ever easy. And there's already a ton of Star Warish games. This is where ED can become truly special.