Fulgurant :
One soda costs $1 per can. Another soda costs $10 per can. By your logic, the latter is an ok buy because $9 isn't that big a deal in the grand scheme of things.
We are talking about the cost efficiency of graphics cards. In some cases, those graphics cards differ in cost by $5-10. If one out of two comparably performing cards costs $10 less up front, but will cost you $50-75 more in electricity, then the other card is irrefutably a better buy.
Your objection is irrelevant to the topic.
If it was only about the soda, then maybe. However, if you were to calculate the price of the soda in reference to the rest of your annual grocery bill, fast food, restaurants, and all other forms of food costs ( especially cost fluctuations ), then that $10 becomes less significant.
I don't think anyone is saying the extra electricity is nothing, we're just saying consider it with everything else you spend money on and the rate at which you pay it. No one is saying the AMD or NVidia model is the better purchase in all cases. However, the slightly higher power consumption also isn't an automatic DQ from any purchase consideration.