With convoke, you can sometimes play the card for free, providing you're going wide enough
Giving the opponent a free Shock is bad enough
You may play those cards during the specified duration even if the permanent with the ability leaves the battlefield or you lose control of it
You don't want to be playing him for seven then passing the turn
While this can add up and did end games in standard, there is a big difference between having 1 opponent at 20 life and 3+ opponents at 40 life each
The theory is that, as Yedora3 brings back non-token creatures as face down and lands, the ability does not remove the interaction between Morph or disguise and being face down - I can morph in a creature, turn it face up for effect, throw it at the enemy to get it killed, bring it back as a face-down card that is a forest, then flip it face up (again) for its morph cost