Why do the Democrats have such a complicated selection process for President?

It seems like the reason this race is dragging on, is becuase of the complicated delegate selection process, for the upcoming election years to prevent the primaries from dragging on, should the Democrats look at making their primaries and caucauses more like the Republicans, with their winner take all states, and being less generous on dividing the delegates. I think the race would have been decided much earlier if that happened.