I actually think regression and verification are secondary purposes of test-driving code, a nice side-effect if you will. The primary purpose is producing more modular, understandable code. It's actually pretty tough to write a big pile of junk when you're being vigilant about test-driving. But I agree with you that TDD/BDD often adds unnecessary overhead when you're writing a prototype or proof-of-concept.

TDD/BDD is a skill that takes work, like any other. It's not like you start doing it and suddenly it's all rainbows and puppies. It's painful and often slower, especially at first. All that said, I'm anti-dogma of any kind. Do what works for you. But know that TDD/BDD is not a magic light switch. It's gonna take time and work to get into the groove of it and become test-infected.