I agree, and it's all quite unfortunate as there is so much to contribute without having to "push off" of prior approaches. I notice this in Marsha Linehan as well, whose material I like and use extensively. I'm just learning ACT, and already find much that I can use in my "traditional" CBT approach. What it offers is a persistent emphasis on becoming aware of and shifting from control strategies, as well as the great values piece. It's also unfortunate that CBT often uses terms like "mastery" because it leads clients (and therapists) to believe that it is about controlling and overpowering anxiety. ACT strategies and explanations help me and my clients watch for the mind's attraction to relating to and controling states of mind, and to frequently lose sight of what's really important and occuring in the present moment.