There's no Schelling point between forcing people to die at some convenient age and be happy and thankful about it, and just painting smiles on everyone's souls.

A statement like that needs a mathematical proof.

If it's a terminal value for most people to suffer and grieve over the loss of individual life

"If" indeed. There is little "evolution-spawned" about it (not that it's a good argument to begin with, trusting the "blind idiot god"), a large chunk of this is cultural. If you dig a bit deeper into the reasons why people mourn and grieve, you can usually find more sensible terminal values. Why don't you give it a go.