That looks to be a nice game (grpahics arent that great though, but a nice idea, I wish we would see more games like this and not the sterotypically blow ppl up)For the exploration! Think Afrika. For some, shooting adversaries and becoming more powerful will be the draw. For others, pootling about in spaceships discovering new creatures will be the draw. It has no set release date, so they can take their time as long as someone is funding it, meaning they can put in as much as they want including alien critters.
the thing is adding the creatures in is going to add another level of difficulty (in an already difficult game) which is going to elay the projects completion date and perhaps make it so it wont get done at all or very delayed. theres plenty of examples of games that have done this eg GT5 (couple of years too late, cause they tried to go to far)
mid 2015 : no mans sky
mid 2017 : no mans sky 2 (now with creatures)