For example: A Blessing in Disguise: a Jungian Reflection on Sunni-Shia Split a recent entry from the Ihsan blog, suggests that the division between Sunnis and Shias has injected a certain amount of life and vitality into the ummah:
[...] this ying-yang type of split between Shia and Sunni schools may have actually helped to maintain a balance in the collective consciousness of both Shia and Sunni Muslims. The presence of different perspectives keeps our conscious attitudes from freezing into a rigid, inflexible, stale position (as it would if we only had one correct view or a perspective) and creates a dynamic movement due to the tension of so-called opposites. Each school of thought prevents each other from petrifying into a stiff, lifeless formality. It may just be that this ying-yang type of conflict has created enough tension to allow for a continuous movement, renewal and growth for each school of thought and for the collective consciousness of the Muslim ummah.
And in The Study of Shi'ism Seyyed Hossein Nasr suggests that the Sunni - Shia split was beneficial because it allowed Islam to reach different kinds of people with diverse spiritual/ethnic/cultural inclinations:
Within each religion [...] especially within those that have been destined for many ethnic groups, different orthodox interpretations of the tradition, of the one heavenly message, have been necessary in order to guarantee the integration of the different psychological and ethnic groupings into a single spiritual perspective. It is difficult to imagine how the Far Eastern peoples could have become Buddhist without the Mahayana school, or some of the Eastern peoples Muslim without Shi'ism. The presence of such divisions within the religious tradition in question does not contradict its inner unity and transcendence. Rather it has been the way of ensuring spiritual unity in a world of diverse cultural and ethnic backgrounds.
Both approaches are appealing. The only question is whether those benefits are really worth the violence and bloodshed and division which are also associated with the split.