Jon,
That is a very good point. When you are in an area where you can grow either warm or cool season, you have to pick your poison. When do you want to be at your best? Make that decision and then pick the appropriate grass. Unfortunately, many decision makers often make that choice and then decide they want to be at their best 365 and that's when the problems develop.
We used to grow good bent in the hot SW because summer play was not a big deal. We used to have some pretty goof bent even in areas like the inland deserts of CA because clubs would close in the summer, or at least not expect great conditions. Now, expectations have changed and we need good golfing conditions all the time. That, IMO, is where the "pushing the grass" comments are rooted.
One other note, someone wrote that the transition zone was anywhere you had two different turfs, usually cool season on the greens and warm season on the fwys. I don't agree with that description as you bring in areas like coastal southern Cal, AZ. NM, central TX.
For me, you know you are in the transition zone when two courses in the same city (maybe even on the same street) have different grasses course wide. When you have different courses with Bermuda, zoysia, blue, and bent fwys, all within 20 miles of each other, you are in the heart of the transition zone. Green's turf isn't really a good indicator of being in a "transition" zone.