The other day I was thinking bitcoin itself is decentralized, but everything around it is centralized or striving towards being centralized. Let's just take a look at this forum for example. Here are certain people in such power that if they decide, they can destroy you - your forum nickname. Members with trust can give you negative trust for no reason and you have no way to fight against that. Admins can ban you with no reason. Isn't that the principle of "centralization" - a few people having power to do anything and with no justified reasons?
But on the other hand if you want to get something done you have to achieve a consensus of all the participants. That is slow and expensive and the world would essentially come to a halt if everything were done that way. Everybody involved should try mining and see how difficult and expensive it is and if you use Bitcoin for any length of time you run up against confirmation issues. It taking too long to be viable in certain use cases and people substitute centralized services (Bitpay, coinbase, etc.) to compensate for that.