I think it's a fair point to say that the game has not been in the oven that long at this point and that due to the nature of its funding, it has been made public at a much earlier stage of production than most other games. However I don't think it mitigates the fact that the design seems all over the place and that Roberts have issues keeping his own schedule. And while it's true that some games had equally protacted production, the reverse is also true with the new Elite having been already released (and apparently with production starting later or at the same point roughly).
The game will be launched in 2016 at the very earliest, right ? Beyond that will start to feel like a long time, even to some backers, I think... I don't think a protacted dev cycle is ever a desirable thing, especially for a small outfit. I would believe they are more frequent at big publishers because of company "politics".
They could hit 100m though.