Fees are just a side effect of the actual usage of a blockchain network. ...
Correct, which is why Monero got it right and has a dynamic fee system that will make fees cheaper as usage increases (inversely proportional), genius work ArticMine.
I'm still confused on why this does not open an attack vector with chain spam? Is there a critical mass point?
Sorry but I stopped reading progress when I couldn't get the info I needed to vet the RPC (at least the "Scientists" found that vector afterwards). Is there a quick synopsis of this discussion, I can never find irc logs.
maybe you should PM ArticMine and ask him directly.