You just don't read to the end of my answer.But, other MMOs have things like story line, inter-character relationship and so on in bedded in the game play. Elite dangerous have non of that, so the end-game is to get a bigger ship. Otherwise you may well being wondering around with no goal or purpose.
Better compare list implemented at the time of release, with a list of what has been done at the moment and try to imagine how much time you would have spent to implement this.The game will be in development for at least another 3-4 years, so what we have at the moment, not the whole content. So, "keep calm and enjoy the game".
The game is in development. At the moment, implementing the basic mechanics of the game. Take for example the game "starcraft", the development of a "game engine" took a few years, and to draw a "new map" will take half an hour.
Why should we pay for the "raw game"?
We pay for the fact that the gameplay became even better. Speaking about "gameplay", in some games you can see much less content, and developers does not plan to change it.
"Elite dangerous" is a game with great potential, we just have to wait for the full content.
And one more thing, the players that will buy the game after 2020, will take it at a much lower price than it will cost for playing players, and rightly so, because we (who have bought the game already) have access to the game already.