However, I will argue against your ideas that sustainable democratic governance is not created through active division of the population. I believe that democracy is easier to achieve where there are bonds that hold the target population together. The idea of power sharing is easier to accept where there is not already a strong distrust. There is trust among homogenous groups. I believe that democracy is actually easier to achieve in a homogenous population than in a sectarian one. I believe the research on the matter will back me up. Again, see http://warontherocks.com/2014/05/dem...obayashi-maru/.
The "bonds" do not necessarily have to be cultural or ethnic. This is a narrative imposed on the majority on the minority to justify the exclusion of the minority from the political process. Those in power do not want to share and deliberately create filters through which to distribute power - this often comes down to ethnicity, religion, race, and so on. The power of a democratic society is not created by its homogenieity but through its plurality in which all groups (or alliance of groups) have similar levels of power and access to power. This is why successful power sharing agreements distribute power rather than separate those seeking it.

Maliki's refusal to share power is invitation by other groups to contest it. The problem is complicated because the most empowered opponents have been so radicalized by the trauma of the War in Iraq, the Arab Spring, and the War in Syria, that the two sides are light years apart in their political positions. Our policy in Iraq and Syria has more or less propelled Al Qaeda from a marginal terrorist threat to one of the most robust movements in the Middle East in decades. It was not sectarian differences that created this problem, but the many years of violence and instability by our failure to create a stable government in Iraq in 2003.