Originally Posted by
Nissa
While you can ask those questions, Niadra is some broad with no real impact on the story or affect on millions of lives. As much as BW did end with Kerri's blood lust being satisfied, along the way it introduced so many new elements with no conclusion or presumable conclusion. Who the hybrids and Xel'Naga are affects everything the Zerg and Protoss stand for, as well as forcing humans to cope with whatever results from this. That's massive. As is Kerrigan leaving alive people (Raynor, Mengsk, Artanis, Zeratul) who have the will to destroy her. This means that war will inevitably happen. Unlike the Overmind's death, which could only imply war or lack of war based on whatever direction Blizz wanted to go with it. Blizz wanted to go with more war, so BW ends up putting the Protoss in a position where their issues will lead them inevitably to conflict.
Think of it like a writer would. If, at the end of a story, the plot can go whatever direction it wants according to the whims of the author, it's settled, and the series can stop there if the author desires. If, however, the plot is limited by the nature of the characters, the nature of their interactions, the status of their setting, and important conflicts unresolved, then the plot is unfinished.