A combination of reasons, none of which had to do with any flaws with the CX-7.
We had an 04 Mazda6 Grand Touring 5 door that we traded for the CX-7. It was the perfect car and the real reason for the trade was high mileage and going out of warranty. (54k).
My wife never got quite used to the size of the CX-7, and drove less often. I drove too often, and too hard. I always had a feeling of resentment when I filled it up too frequently, and with 93 octane, at that. We got restless. I guess I siezed the opportunity to trade while I could wind up with a lower payoff on the new car, and lower payments at the same time.
Like I said, I'll miss the power, but I'm back in familiar surroundings, and (as much as it has been discussed, I don't want to start an argument here) I feel the interior appointment of the six is more tasteful, and has more creature comforts.