@Ian W - My impression is that the points you mention (GPS mod, batt life, expense, charging, transoceanic routes, ...) all make sense. And should be included in discussions in solving the issues that have become clear with (RedSea), AF447, MH370, AirAsia, and now Egyptair.
One of the issues that has to be solved is what the cost of such a search is. You need that to focus the related solution efforts (engineering, manufacturing, operations, maintenance, training, etc). That would require a very serious effort by itself. The perception of people and parties in this respect varies wildly and is changing. The Australian government for example had the opinion early in the search for MH370 that 'we have these assets anyway, so there is no cost'. They have been forced to change their opinion since. The Fugro contract is an example of part of a possible search cost.
I have collected data during the MH370 and AirAsia searches and used that to make an estimate of the actual cost of such an effort. The numbers get very very big. How big, that depends for instance on how much of the cost of a SAR infrastructure, and shared use of military resources is allocated to a specific search. Such an allocation means that insurers and airlines would never be charged the 'full costs'. In that sense in the end it would probably look more like setting a 'price'. Where the price is lower than the cost.