I bought witcher 3 and I don't expect anything more from it other than bug fixes... but this is because the game was actually finished before release. It wasn't kickstarted based on a bunch of promises, then released with only 1/3 of them met, then development resources expended on two new large features that hadn't previously been mentioned and which were largely unwanted.
Expectations in this case are a direct result of unmet promises.
I think some people have mixed up "promises" with open design discussion.
It's easier to stand back from a game like the Witcher and say it's finished because the design corrals the player down a particular narrative with a far more finite number of things which need to be expanded and tested.
When you crowd-fund something you have to accept you are taking a risk and shouldn't be jumping to preconceptions about what the delivered product will be like.
Otherwise you should take the option to purchase the title on release day at which point there are reviews/documents available which indicate what has been delivered up to that point.
As a fourth game in the Elite series I don't feel that it's particularly incomplete, as an open world online space game I'd say it delivers more than most. I guess I just don't feel any developer will deliver what every person wants in one open world game in this genre in one release. Past games have demonstrated the difficulty. The expansions are part of the funding model that keeps this game going but the base game continues to get build along the way. If Frontier have no business plan beyond unit sales I can't see them making the game everyone wants.