How do you judge when the system becomes too centralised, particularely when it comes to nodes?
You guys have been suggesting the market is interested is in a global payment network/currency unrestricted by a transaction bottleneck. A more centralized network offers exactly that.
Are you not worried that miners can slowly capture the participants up until a point where they control a great majority of the network nodes and can trivially change protocol rules? At which point users might be presented with a choice to stay at the behest of miners and assume that they will act in everyone's interest or fork the coin and risk severely undermining the trust in cryptocurrencies in general (causing important financial losses).
I guess nearing 50% hashrate centralization is enough for the market to start panicking as shown by the Ghash episode and another similar episode with another pool which I can't recall ATM.
We all know the advantages decentralized system have over centralised one. And no, I don't think a centralized miner will be able to fool everyone as long as the system remains open. The blockchain is too heavily monitored for this to happen.
See here:
What really matters to miners is a market thinking that mining is decentralized, not a really decentralized mining ecosystem.
It's important to remember that most (all ?) available statistics describing the (de)centralization of mining rely on weak (and easy to cheat) heuristics.
Also you have again conveniently ignored my point that hashrate centralization is not the only centralization concern.