Douglas Back built Widget the People, a tool that lets you create an embeddable thermometer showing how many signatures your petition needs before it reaches the responsethreshold.
When the Obama team created We The People, they may not have thought too much about all the ridiculous and just-for-fun petitions that would reach the threshold and thus require a response (or maybe they did, and embraced it).
Update: The signatures threshold for petitions on the We the People platform to receive an official response from the White House has changed since this blog post was published.