R12: GL Secondary Ledger Conversion Level Change

In today's installment of "did you know" for R12, the short article "GL Secondary Ledger Conversion Level Change" in note 1614737.1 stirs up more questions than answers for me.  First off you can't enable a conversion of a secondary ledger once disabled, but that makes me wonder why you would want to disable it and what the business implications are if you get to the point you need it enabled again.