Most of your points sound good here are a few more.
As Robin pointed out maintaining fidelity in the germ line requires a
lot of energy. There is a very large burst of gene repair activity
involved. It would be to costly (for poor primitive genes) to maintain
the whole body that well in the world we evolved in. Also there is a
balance between optimal mutation rates for adaptive change and the cost
of those mutations in terms of survival.
Genes are not the only thing competing for survival here. Most of the
things that are relatively poor at surviving are not very well
represented in the world. I don't think that bodies have ever passively
accepted a role as mere carriers of the genes but they also compete
with the genes they carry. The process of life goes on at many
different levels simultaneously. I would like to get a better
understanding of processes on a larger scale than me.
-- I. William Wiser <wwiser@best.com> Longevity Consultant