Quick way to cash in the opportunity. But it makes sense WWE gave Swagger a quick run as Mr. MITB - in 4 months a new PPV will come, named "Money In The Bank". Certainly don't want two briefcase holders at the same time.
I think WWE's trying to capitalize on the number of veterans available that can help raise profiles of promising rookies - Cody and Ted had Orton, Sheamus had Cena, and Swagger got Edge and Jericho. Not to mention NXT.