TDD/BDD approach can definitely work and result in higher cohesion between the requirements, design and implementation phases.
The trick is to make sure all phases of the project are factoring this in - requirements with clearly defined user stories and acceptance criteria; design docs where each acceptance criteria is covered, etc.
Another thing to point out is "TDD" is a balancing act between integration and unit tests. There's also a balancing act between the external tests driven by the dedicated test tool and internal tests included into the app.
The trick is to make sure all phases of the project are factoring this in - requirements with clearly defined user stories and acceptance criteria; design docs where each acceptance criteria is covered, etc.
Another thing to point out is "TDD" is a balancing act between integration and unit tests. There's also a balancing act between the external tests driven by the dedicated test tool and internal tests included into the app.