It is rare that a packs off departure is REQUIRED for performance on the 747-400.
In those circumstances, an APU to Pack 2 procedure is available to provide maximum payload, while providing air conditioning until engine bleed air is restored.
However, most departures from airfields below, say, 3000ft amsl, will see packs re-instated before the cabin climbs above 5000ft, which should be of no discomfort to the passengers.
In these circumstances, it saves engine wear and tear and thus promotes engine life and saves costs, to perform a 'bleeds off' take off. This allows take off at a lower thrust level, with reduced EGT's. As a consequence, it helps to keep down ticket costs!
For me, in my company, the flexibility to use an APU to pack take off has been removed, I see this as an ill-thought out procedure that fails to recognise the few stations (eg NBO, JNB, MEX) where it would be beneficial in the event of an engine failure for the expedience of a single procedure that saves a bit of fuel.
It should be an available procedure for use at the Captains discretion.