A lot of people are upset already that you not only can't defend belts on Raw, Smackdown or Superstars, but also... you cannot set up title defenses on PPV's yourself.
If a belt isn't being defended in a PPV main event then you can't make it so. You can change the participants but that's it.
There is a way around this, it seems. It's actually rather more a glitch you can activate.
Go into the exhibition and switch the Superstar's currently held title from one of the "main 4 titles" (like the WWE Title) into one of the Unlockable titles (Like the WCW title), then head back to Universe and defend it. The match as you set it up, will be fought for the WWE Title.