As someone who was not a kickstarter backer, I came in at premium beta, the people asking for a refund seem, at least in my opinion, being a little unreasonable. Looking at the development so far, this is a great game, and a worthy successor the the Elite lineage.
A quick search of the Kickstarter main page, the principal advertising document for the KS, the word "offline" does not appear. Now I haven't watched all the videos, nor visited all the links on that page, but if your pledge choice does not indicate the presence of an offline mode, then frankly, you can't really say that one should be provided to you. Also as backer to other projects on KS, projects that have not been delivered upon after waiting for 26 months, with no advanced access mind you, I have never been offered a refund for a KS project.
I am sure, that Mr Braben loves this game, and also that Mr Braben and the Frontier team, and company, would like to reap the financial benefits of constructing this game. Some form of online connection ensures that 1/ People who are playing are also paying, and 2/ A dynamic universe based on PC, and NPC events and interactions can develop the game beyond what is possible with a one time static download. Both these things benefit the player base.
I speculate, that if Mr Braben and Frontier could no longer sustain an online presence, that they would want to find a way to preserve, if only for themselves, the game in playable state. To this end I would speculate further, that in this circumstance, Mr Braben and the Frontier team, would make available either a standalone version of the game, or a server mountable version that users could host themselves.
Now if you do not want to rely on my speculation of Mr B, and FD, and you love this game and genuinely want an offline mode, then go buy some shares in FD, and at the next AGM, put your hand up and ask why you cannot have it. As a shareholder, you will get some serious attention.
Turning around, after having played the game up to now, and saying it sucks because you cannot have offline play, and you want your money back, well to be frank, it seems like a kid throwing a tantrum. (yeah I know this is inflamatory, but that is the way alot of you read to me)
Play the game, or don't play the game. If you are leaving over this, thanks for testing this game up to this point, hope you can see your way past your difficulty with offline mode, and join us again soon. Your account will be waiting for you.