2) similar to the author's point that advocates can't tell the difference between "store" and "medium" of value, I can't tell you the number of arguments I've gotten in with people who equate a "store of value" to be the same thing as the "increase in value"
3) It's a 1% wet dream. Make money, potentially hidden income, avoid taxation? No money paid into the welfare state? WIN!
From a logical standpoint, "so does X" (e.g gold mining) very much does eradicate this as an argument against BitCoin, unless there is some Y which has less carbon footprint than either. If there is not, then the carbon footprint it's an necessary evil, and a constant through all similar systems.
And an even better question would also ask, "What's the carbon footprint of not having a government creating more money?"
I'm not saying bitcoin replaces all those things (it certainly doesn't), but it aims to.
Right now one of the main metrics people use when evaluating the profitability mining hardware is Ghash/Watt, so the market is naturally incentivizing low OpEx and therefore less power usage (per transaction processed not the nominal amount of power used).
Also, it's actually more efficient to have a smaller number of machines running at full utilization 24x7 than the typical massive datacenter that averages around 20-30% utilization [0]. That's because modern servers consume nearly as much power at 20-30% utilization as they do at 100%.
[0] - http://bnrg.eecs.berkeley.edu/~randy/Courses/CS294.F09/whare... (page 55)
There will always be central banking infrastructure controlled by billionaires who are more socially important than you. We can't just "go decentralized." An average person is too busy to even remember their password to gmail is "password456" and not "password123."
On top of that, you have to consider that those systems offer much more value than just a barebones ledger as the core of Bitcoin does. If you add in all those companies building stuff on top of Bitcoin, the comparison starts to become less favorable.
[0] Purely monetary terms are obviously different. The vendors of those systems inflate prices ridiculously because they can - banks have traditionally not been under much pressure to operate efficiently in this arena.
Since miners will eventually only be able to compete based cost of their electricity mining will be driven to places with extremely cheap electricity. I don't know if that will always correlate with "clean" energy, but it seems like it would. For example, the recently announced Bitcoin mining operation in Iceland, where cheap geothermal and hydroelectric electricity and plenty of cold air for cooling is available: http://dealbook.nytimes.com/2013/12/23/morning-agenda-the-bi...
If the heat from mining can be reclaimed for other purposes (heating homes, etc), then the effective carbon footprint is reduced even further.
It will hopefully make clear that your argument is flawed.