/bin/bash won't usually ship with a BSDish OS because of the license, so it is not generally portable to use bash-isms. (HPUX, IRIX, SunOS, Solaris, etc. I don't reckon would have had bash either)
Not to mention once installed on a BSD it would most likely reside in /usr/bin/bash (OpenBSD for instance)
Or /usr/local/bin/bash (on FreeBSD).
I disagree.
You are also right.
Now that I saw tingletech comment I got your point :)