I will summarize my opinion about this in 4 simple sentences:
1) When a game has a gameplayability value over 150h, it is a game worth its price.
2) It is normal to eventually grow bored of any game, no matter how good it is.
3) I have played more than 6 weeks to the game. Which in hours is over 1000h.
4) Elite: Dangerous IS a good game.
Still worth improving? Certainly. But to say "I want Elite to succeed" is an understatement: Elite: Dangerous has already succeeded.
What you say is true, but Elite is a living breathing MMO according to its advertising etc,
Instead what Elite is turning out to be is and barebones game, that is becoming more fully furnished release title with each update.
Elite is indeed a fantastic game, If you buy it today, and play it for 150 hrs you will be well served and satisfied, but Elite cant be measured with with that yardstick.
Backers that bought the game "way back when" play for 150 hours and must be satisfied? whereas the person that buys today plays for 150 hours and gets a much better experience.
Elite isnt a single player game, it doesnt have a, "after 150 hours you must be satisfied you got your money's worth and move on" vibe, its an ongoing MMO/Multiplayer online game,
it needs to cater to old, current and new players on an ongoing basis...
Lets take Witcher 3, that also has 100ish hours in the base game.... Imagine they brought out the Expansion Hearts and stone... and all they added was some more swords and a new monster or 2.... People would revolt, the expansion must come with new missions, more story, more stuff to do, expand on your current savegame.... not expect you to wipe your save.
Elite is currently putting things into the game that look good on the feature list when selling the game to new Consumers... but leaving their old consumers to... well complain on the forum.
When updating the game, they need to think.... Right... I've been playing the game for ~1000 hours (avg for a seasoned player).... what can we put in the game that will add value to Johnny thousand hours that has done x y and z 100 times over.
What we get now is a turret mode where Johnny thousand hours can sit in a friends ship and do the same thing he has done to death, but now from a different view..
See what I'm getting at?