My argument in favor of AAA is the mess made of pitching stamina in the past decade. To get enough SP innings, most of our draft teams will need at least 6 and probably 7 pitchers who can go 5+ IP/G. And because we are dependent on the average IP/G thrown instead of what guys are capable of throwing, we'll need deep bullpens. In 2009 there were 74 pitchers who went 6+ IP/G, but 112 MORE who threw 5-6 IP/G. In real life, those 112 pitchers were mostly capable of going 7-8 innings at times, but we can't do that. The AAA P are necessary, IMHO.
And I always like having AAA hitters, just for the fun of it.