Because it's just plain true !

Clearly you won't see much of a difference on your electricity bill if you use a more efficient light bulb, a more efficient fridge, tv or whatever else. Now imagine all theses "not much a difference" cumulated on your neighborhood, area, town, region, country and you'll understand why those makes really a sense.

People wouldn't buy a "more efficient" product because there wouldn't be really many more "efficient products" but rather a larger lobby (GE, and other major electronic manufacturer) to build more "clean energy sources".

And don't forget that the biggest electricity users are the companies taxing them for over usage could be quite critical as some are rather hungry (you know big machineries and so on...)

Not that I never used a "long term evaluation copy" before BUT the usage of virtualmachines (no sound, no networking, no nada) was the best way to launch said keygenerators to generate what was needed.

No need to worry about your system being now part of a botnet as you are going to delete the whole image just after that (or keep it deeply infected if you have a large turnover...)

But as many many said the best solution is to buy the software.