I've heard people comment that tai chi chuan cannot be used in self defence... or that the bagua palm changes are a training method rather than martial...
These comments/opinions tell me two things:
1. The person saying them cannot personally apply these arts
2. They have not attended our school
It is dangerous to generalise about martial arts; applicability rests in the hands of the instructor. The better your instructor, the more they can do with the tools they have been given.