Yea there is a good point here. What is the ideal emission curve vs should the emission curve be changed at all are two entirely separate questions. My reply was more along the lines of what would be the most ideal emission curve and not any claim about whether it should be changed.

As for the arbitrary nature of these decisions yes i agree, it is very arbitrary and non adaptable. I think this is a very strong legitimate criticism about all crypto in general. Ideally we would have market feedback that would allow us to adapt these values to the optimal level, that is the level at which all attacks that are prevented by said emission would be avoided but only just. But there is no way to measure and determine what this value use. Not in any verifiable way. If we were to make it variable, it would end up coming down to the decisions of individuals which opens up room for corruption. It would be a bit like having a crypto federal reserve. Not ideal.

Right now the mechanism we have, and the only one that we may ever have, is market competition between different cryptos. Where the ones that select the best static values gain capitalization and the ones that chose bad static values lose it. Its slow, cumbersome, and non addaptive but it is perhaps the best answer we will ever have to this problem. (other than proof of stake which has its own shortcomings).

also the block chain may be able to sense if it is not secure enough, but another big problem that people often over look, and something that it never could sense, is whether it is paying too much for security. Miners can see if there are long orphan chains than perhaps the reward should be raised. But even then it opens up new attack vectors for fraud with people purposefully crafting long orphan chains inorder to change the reward.