If you don't see that Ortiz is EXACTLY a tuneup for Pacquaio, you're fooling yourselves.
Mayweather is going against what? A young, fast, extremely hard hitting southpaw who isn't as skilled as Pac but has the raw talents just the same. This is Pac-lite. If he can defeat, maybe even dominate Ortiz, who is bigger, stronger, and more powerful, Mayweather will finally convince himself that he can take on Pacquaio and beat him.
On the other end, Pac is fighting Marquez, who is a smaller, slightly less skilled version of Mayweather. Sure, Marquez is more willing to mix it up and leaves himself open far more, but he's a fighter who relies completely on his straight right hand, who likes counterpunching, and is prone to not only think during fights, but make huge adjustments in strategy depending what the situation calls for.
In a way, they are both fighting less skilled versions of the other fighter.
These fights will be the Spanish Civil war to May and Pac's World War II- a testing ground, and the precursor to, the biggest battle in years.
If they both win, I bet the fight FINALLY gets signed for May of next year.