You also have to realize, this could be different on any given year. If there was only one playoff team from each division, if there was one standout team from each division, those playoff races could be pretty much done as well. I recall one occasion a few years back when the Yankees pretty much had the division locked up, but in August, the Red Sox were fighting with the Rangers for the wild card.
The three game series that the MLB is discussing will accomplish two things. One, more teams will be involved in the playoff hunt, and two, it will give teams a reason to want to win their division.