The big problem with space games is that they're set in space. Space, by definition, is almost entirely empty and extremely large, so there's very big gaps between the interesting things.
Most game designers conclude that designing a fun playable game is tough enough without deliberately picking a setting that is hard to make fun.
Those that do deal with it in different ways:
1) Restrict the scope. You could fit the entire Elite Dangerous player base, all 2 million of them, into Saturn's rings at the same time without anyone being within 100km of anyone else. If you kept travel speeds relatively conventional, no magical fast travel, then it would take longer to get to the other side of the rings than it does to reach Beagle Point from Sol in Elite Dangerous. The game world would not be "small" in any conventional sense.
And yet, "one planet" seems ridiculously small for a space game.
2) Cartoon scale. Make the stars and planets much smaller than they really are, and much closer together. It's not realistic, and it makes planetary landings much harder to implement, but it lets you pack all the action together. The original Elite did this, and so do lots of other games.
But, again, why set a game in space at all if you don't want to deal with the actual "space" bit?
3) Extreme templating. Have the full scale, or at least tens of thousands of systems, but rely on random generation building up from templates for basically all of it. Also done in the original Elite, but more so in Frontier Elite II and Elite Dangerous. Obviously has the problem that 99.99% of situations generated will be very recognisable variations on the first few hundred things you saw.
So you get the problem Elite Dangerous has - how to make seeing the same thing for the 100th time interesting? If there are millions of systems, why care about any individual one?
Given that, it's never possible to keep everyone happy - if you make the game big enough to be worth setting in space, it's too empty and repetitive, it takes too long to get from one side to another, etc. If you make it smaller so you can fill it with interesting things, people will complain that it's too small and they can't go where they want to, and you may as well have just set it on one planet (planets are still pretty big!) and not raised people's expectations unreasonably.
Given the choice between that and making a more traditional FPS (explosions! action!) or management sim (numbers go up!) with well-defined and well-understood gameplay, it's hardly a surprise that there's been no big rush to the genre.
I think it's very unlikely that any game will come along that beats Elite Dangerous *on its own terms* - massive galaxy, first person, multiplayer - in the lifetime of Elite Dangerous. It wouldn't be impossible to do - but there's no sign that anyone is trying, and the longer that goes on the more of a head start ED gets.
There are plenty of other niches for a space game to fill, though - and more signs that people might be trying to. Whether they're "better" than Elite Dangerous might well depend on what exactly someone is looking for in a space game considerably more than on the details of implementation quality (was Frontier Elite 2 better or worse than Freespace 2?)