They still gave the backers the basics of what was pitched in the kickstarter, it had all the basic features that was planned to be included in the kickstarter so they give backers what they planned plus more by the end of 2015 and even more onto of that by the end of 2016.
Why is it not ok for a game to develop a game as much as it is needed, thats why most of the game released recently are not as good as they can be as most need at least another year to be really ready for release, RDR2 got about 7 years development for a PC release and it was still not ready to be released, a game should take as long as it needs to be ready for release, not just rushed out for no reason other than they want to push it out.