I don't like the idea of handing over my contributions to another party under their terms. Either release software under a common open source license (BSD, MIT) or not. Don't add additional terms with some custom license that certainly wouldn't help me.
I contribute pull requests to quite a few github projects. However I avoid contributing to (or even using) projects with a Contributor License Agreement. Such projects are too bureaucratic.
Not the case - they can claim it is so, but a BSD license with extra clauses is not a BSD license.