“My soul is sick of the back-and-forth in Ashenvale that has gone on nearly since we set foot in this world. And I am even more sickened by our own blindness to what we should and must do. The night elves claim compassion and wisdom, yet they murder us when we harvest a few trees that would provide life-giving shelter! The night elves have lived here long enough. Let them now linger only as a bad memory. It is the Horde’s hour to reign on this continent, and reign we shall!” - Garrosh Hellscream
Ashenvale was the primary cause of Alliance and Horde's tensions in Kalimdor -- Durotar and Orgrimmar lacked the essential resources to sustain their population properly after the Third War, and the night elves seemed less than willing to provide them. It has been a major point of conflict -- in the original game, Cataclysm, in the Fourth War, etc.
As far as we know, Tyrande giving Azshara to the Horde was able to guarantee at least several years of peace, as the Horde abandoned most of their outposts in Ashenvale.
What if Tyrande and her night elves just gave the orcs half their territory? Would that have settled tensions between them permanently, and perhaps even averted or settled the Alliance-Horde faction conflict once and for all?