While I wait for your next post, here's a sketch of the two major objections as I see them. First, the US needs to guarantee the free flow of oil. This article (via Instapundit) is quite good on this point. And second, doesn't withdrawal assume that the regimes in the middle-east are only threats to one another and not to the US? And isn't that assumption false?
Plus, since when has turning tail and running been a good strategy for getting a bully to leave you in peace? Our flight from the middle east would simply embolden and enrich al Qaeda. Where would we be leaving next? Turkey is a good bet. The Philippines. Pakistan. And how long before others learn and apply the lesson? Won't we look forward to the day FARC stops importing IRA bombers and instead imports al Qaeda bombers? If 20 guys with a million dollars can set US foreign policy, that opens the door to a lot of players.
If we withdraw from the middle east, we must at least establish that we have not done so out of fear. We must smash al Qaeda first, and then exit on our own terms. Anything short would be an open invitation to further mass terrorism.