It's not my intention to question the freedom of people to use bitcoins or watch Nascar. There's one critical difference: in the case of bitcoin the resources employed to mint it are part of the economic design, it's not the desired end result. Free people want a monetary and transaction system and the incentive structure built into bitcoin encourage them to expend resources towards that goal. So if a better system can be designed that offers the same freedom and features with less resource expenditure, everybody is better off and you can objectively call bitcoin "wasteful" by comparison. Whereas the whole point of Nascar is having people's run around with their ass on fire, there's no waste because that's the end goal.
that's right, money is just information. However, it has to be secured, in one way or another. We also expend lots of resources on door locks. We don't live in a perfect world unfortunately.
We should discern the minting part of bitcoin (disbursing new coins in existence) from the consensus algorithm (keeping transaction with existing coins safe from double spend). Bitcoin cleverly conflates them during initial bootstrap so that sufficient security exists despite not much transactions going on, but they are really two different problems.
For the purpose of this discussion let's ignore Ripple and it's ilk and posit that proof of work is the only way to achieve reasonable security in a distributed system. Well, then we should design the system so that it can prevent a given double spend size (say, 1 million dollars), compute how much proof of work we need for that goal, and limit the block reward at that level. We could have a 1 trillion dollar economy on top of this network, it's just that those accepting large payments should spread them out in multiple blocks no larger than 1 million dollars. Hardly a major issue and it caps the energy waste to a negligible level.
This leaves us with the initial distribution problem. It is here where the "proof of work" vs gold parallel exists. There's no fundamental reason that we should waste resources to bring money into existence. We could design quite a number of "fair" schemes that don't involve "mining": gift every person in the country with 10 coins, allot them by lottery to a list of charities etc. OpenCoin decided to gift itself with the whole 100 bln XRP, hardly a fair scheme but again, no resource waste.
@marcus: So I see you have detected the skillful errors I've planted in my calculations. Illuminate us all, if you please.