Eddie,
Yes, the de-baathification did alot to alienate the standing powerbase in the Sunni sectors. Particularly in Al Anbar. Though I dont think it was the most significant factor.
It may have been a bad idea. But at the time there were some serious fears of bigger problems if they were left in place. They had significant combat power and we had inadequate forces in place to hold it together if one year later they put something together. Remember, we had "won" with a small force and pressure was on to reduce the footprint in theatre before the Abrams had even shut down their engines.
Its a hotly contested decision but pinning the insurgency on it alone or it "mostly" is short sighted. I'de bet that without hindsight most others in Amb Bremmer's position would have done something at least similar.
The insurgency in the south was an altogether different animal and remains such.