pretty sure the only reason they haven't done it is because 1. Rick Moranis is pretty much done making movies, he's turned down everything from Ghostbusters on. 2. Episode 1 was so bad that Brooks couldn't think of a way to parody it without coming off looking like a direct mockery of how bad it was.
Hm. We could make Yogurt CG. Then he could do backflips and shit. And since John Candy's not around we could replace Barf with like a rastafarian rabbit or something. Maybe get Adam Sandler and tell him to really ham it up. Rick Moranis doesn't really act much anymore so we'll have to replace him too. Those are pretty big shoes to fill though so maybe replace him with somebody kind of brooding and angsty, y'know to contrast. What's that guy from Twilight doing these days? Those movies were hilarious. Shit and Dot Matrix is dead too. I can't really think of anybody to replace Joan Rivers though so let's just splice together old footage of her and use that. Probably nobody will notice.
A prequel to the sequel of the prequel? Now i want a movie detailing how planet spaceball used all the air.