If you measured the cost to the world's airlines of carrying your extra 100kg for the life of an airframe vs the cost of (I think it's) two gear up landings like this one in the history of the 767, I suspect you'd find the costs outweigh the benefits by a fair margin.
Maybe I'm a bit too cynical, but I think you just described most of insurance industry (especially when you include AIG).
Of course, if Boeing did have some sort of sacrificial material for gear up landing they kinda open themselves up for landing gear and termite jokes from the competition towards potential customers...