Some of the theoretical advantages of a plural executive branch are that:
a) there is a clear chain of command within the executive branch, and therefore less internal rivalries and greater cohesion.
b) the voters decide who heads key executive departments in the state government, and these top executive officials can control each other (e.g., the Attorney General can investigate the Governor without fearing being fired).
c) the Governor can replace at will other executive department heads (e.g., the Secretary of State, the Attorney General, the State Treasurer...), thus making the executive branch easier to manage for the Governor.
d) None of the above.