Nonsense. No one will burn more energy to create bitcoins than those bitcoins are worth, the limit is market price. And if you think bitcoin is burning more energy than the existing banking system, well then you're just not in touch with reality my friend.
> And, other digital currency implementation don't require 'mining' at all; just the paranoid ones.
Which is why all of those other coins are little more than failed experiments; lacking proof of work, you lose the main feature of bitcoin, trust-less transactions. None of the other ideas work to achieve the actual goal of a digital currency, trust-less transactions.