It shouldn't be too difficult.

If you compare the schemas of the two databases, it looks like someone
took the MSCRM schema and squeezed it through MAPI and ended up with
the BCM schema. So converting from BCM to MSCRM is a matter of throwing
away the Outlook/MAPI specific columns, and then mapping the remaining
fields back to MSCRM.

It's a little tedious but doable. And once someone does it once they
can post the SQL script to the newsgroup so that anyone else so
inclined can use it.

An alternative is for MSCRM to read exported BCM XML files. Again not
rocket science, but someone has to do it once.

I doubt this is desirable, let alone a high priority, for BCM, but you
can probably lobby MSCRM to write such a script. Jump up and down, wave
your arms, and make a stink. But do it in their newsgroup,
microsoft.public.crm, ok?

If MSCRM won't do it, I bet someone could write such a software, and
recoup the cost by selling it for a modest sum to each of the parties
that's been asking for such.