Anthony,
I think it is a combination of several factors. The northeast/west and midwest certainly have many great courses that are a good fit for championships.
Given that the bigger championships are held in the summer and given that most of the "better" southern courses felt the need to have bent which is at its weakest during this time, it made sense not to try and host a championship and push the bent greens beyond what they me capable of that time of year.
I do think the ultradwarfs are excellent grasses and certainly worthy and capable of attaining firm and fast conditions suitable for a championship--we just have to convince the USGA that there are some courses worth playing their championships on down south!
I wish we had a great course in GA that was available in the summer--still waiting
I am with Mike in hoping that as the "better" courses move to bermuda and people realize how good it can be at certain times of the year, the stigma of bermuda greens will go away.
But, people also need to recognize that for the transition zone, there is no silver bullet and whichever way you go, there are always turf care issues.