The Sultan, The Piasecki disaster was down to poor engineering of the frame which attempted to link everything rigidly together. To cite that as a reason to not try a totally different idea does not make sense to me.
The extra hazards of a multi helicopter lift are clearly evident, which is why flying the helicopters remotely and using software to control their relative positioning would seem the way to go.
Ship to shore movement of heavier military equipment is the obvious application, where cliffs or a rugged shoreline rule out landing ships and hovercraft. There are plenty of civil applications, although breaking down into single helicopter lumps is likely to be more cost effective for most.
Fareastdriver, Chartered Mi-26s were used in Afghanistan, so someone must have felt the extra lifting capacity was worth buying in.