Why Does Fostering a Strong Sense of Catholic Identity Require A Restrictive View of the Role of Lay Persons?

NCR reports today on the Vatican's decision to veto an election by the Maryknolls that would have resulted in a religious brother holding the position regional superior of the United States for the Maryknolls.  The Vatican directed thata priest be chosen for the role.  What prompts my post is the following:

"More broadly, the reluctance to see religious brothers elected to positions of authority over priests is part of a long-simmering debate in the church over how much power a lay person may exercise. ... The Vatican's tendency towards a restrictive view of the capacity of lay persons to exercise governance is generally understood as part of an effort to preserve the distinctiveness of the ordained priesthood, which in turn is driven by a desire to foster a strong sense of Catholic identity in contrast with secularism... " 

My post title poses the question I have in reading this: why does the desire to foster a strong sense of Catholic identity require that we have a restrictive view of the role of lay persons to exercise governance?  We can certainly "preserve the distinctiveness of the ordained priesthood" (who, after all, are the only ones with certain authority, such as their role with respect to the sacraments of the Eucharist and Reconciliation), without saying lay persons can not exercise any governance authority.  In what sense would appointment of a brother who has held various positions of authority and who was elected by a group primarily composed of priests fail to foster a strong sense of Catholic identity?