Of course it is entirely true that built-up areas cannot be avoided around LHR given that it is hemmed in on all sides, but the industry cannot ignore the potential consequences of relegating this aspect of safety to the point of a quick decision in the event of an emergency.
I think you are right NoD - a worst case scenario would strongly increase political pressure for Boris island to the point that LHR would be history. Indeed this may yet result from this incident if the AAIB blames BA procedures and questions the return to LHR from a public safety perspective - BA's case for a third runway will be seriously undermined. Such a situation would call into question the whole way maintenance is managed and carried out, which would mean very difficult questions for the CAA, BA and individuals managing and doing the work.
Over-worked, under-staffed and under-qualified maintenance staff suggests under-paid maintenace staff. But none of that can in any way excuse not knowing how to, or worse forgetting to, fasten the cowls to the engine. And it is entirely legitimate to ask why it was not picked up in pre-flight checks, if only to ensure changes make such an invent less likely.