Depth.
Missions: All the factions have exactly the same type of missions with the same descriptions. Also none of the factions have their own story mission lines. For all you know you could name the factions "faction a, faction b, faction c" and everything would be the same. Like there is nothing unique to it other than the endgame reward.. Like yes i understand the whole "sandbox make your own excitement" type of thing however just because you have a choice doesnt mean that there should be no information at all. For example X3 is also a sandbox and you can make your own game however theres 9 or 12 different faction story lines that you complete if you'd like and each one is unique to the culture of the faction/race. You could of course blow the faction from the face of the game and take over all the systems with your fleet of ships.
The mission types are very boring. Go find this guy in blah system and kill him.. so for the next half an hr you're stuck dropping in and out of cruise to look for 1 target.
Then theres the donation missions.. those are worst of all because they kill ALL type of immersion. "give us money and buy some rep... only you're gonna have to do it 500 times." It would be more RP to just spend 20 mill at once and get enough rep to rank up to max rank..
What else is there.. trading. Trading is pretty well done in ED. The only thing missing is there should be a log book of the prices and items from your last visit to station "a".
Theres no NPC voice comms. This kills the immersion big time. When you get interdicted by an npc, they should tell you that in voice comms. When you attack an enemy, same thing. When you're scanned, same thing etc.
Next is a big one.. the systems.. there is absolutely nothing memorable a system other than the sun. Theres 400 billion star systems.. you telling me that every single star system is well formed? Not a single one is still in the early state where it's still just a nebula? What about the asteroid fields? Where did those disappear to?
Faction home systems.. currently theres no difference between a faction home system that is suppose to be alive with billions of people population and an empty system in the middle of no where. Imagine if the streets of New York were empty.. No people, no travelers, no shoppers, no security, just empty.
ED lacks depth big time.