Last night I watched the NOVA series "Solar System", the episode devoted to Storm Worlds with their own weather systems--Venus, Mars, Jupiter, and Titan. Scientists explained that Earth's weather is mainly caused by our planet being round, meaning that it's impossible for the Sun to heat all of our world at once. Temperature variation between the day and night sides drives the movement of the atmosphere, which results in weather.
This wouldn't happen if Earth was flat.
Compared to actual science, your Crater Earth fantasy is, in the words of Wonkette, weak sad poop.