The fact that my death is a trauma for others also motivates me not to die. Doesn't it motivate you?

Absolutely. But that is a completely separate issue.

However, I sense that is related to some of what is happening when people speak about death in regard to opportunity costs. When mourning the loss of a younger person, it is common to hear people say "S/he had so much potential that now is lost." I've said that before.

But what are we really saying? What did somebody who is no longer conscious or aware in anyway really "lose"?

In reality, and as you point out, we the still living are the one who are losing something. We lose a friend or a family member. We may lose a bit of motivation when confronted with that reminder of our eventual mortality. Or maybe we lose some peace of mind (or add some anxiety) for the same reason.

It isn't my argument that death isn't bad for those who keep living. I would argue their loss would be mitigated if (a) the associated negative aspects of death (pain, trauma, aging, disease, etc.) were eliminated and (b) they meditated on the actual, practical implications of death for the deceased.