I guess you favorite saying is... "Time is gold" ???
I pay for my games, not for the coins. Its a rewards program. EVERYTHING you get there is free. But whatever.
If it was free, then you wouldn't be spending your time and opinion on surveys. They're getting something from you of value to them and using the allure of "points" to get you to volunteer marketing data they'd otherwise wouldn't have. Free implies they're just giving stuff away, but what you've really done is worked for them by filling out their survey and in turn they give you some coins. Its no different than those "Free" MMO offers where you fill out like a dozen surveys to earn enough of that MMO cash currency to buy an item like a shoe or something. If it was free, then it'd be given to you with no effort on your part. Your time is worth something of value, and that value is subjective on the circumstance. Free is getting, for time you don't have to spend.
Having a free sample at a grocery store is free, having to sign something before you can have a free sample at a grocery market isn't free. I wouldn't say Time is gold, I'd say Time is money, but more accurately it's Money is Time. Just ignore the Club Nintendo BS for a moment, the one point I'd like to make is that if you had to put any of your time or effort into something, then that something isn't free, regardless of how you feel about your wallet.
Giving x to get y isn't free. Free is getting y without giving x.
The Club Nintendo rewards aren't for buying games, its for your opinions and feedback for those games. The "rewards" program is more beneficial to Nintendo as a source of metadata and any marketing specialist would tell you that one person's opinions on 8-10 games has far more value and use to them than the spare change it took to print paper goods per unit and the cost to ship it. Depending on how you look at it, you could say Nintendo is cheating you, especially now more than ever because digital content is effortlessly replicated and distributed. Otherwise you'd be instantly rewarded coins when registering a game without a survey required.
Besides, I don't know how old you are, but you should atleast heard it enough by now that we live in an age of information, and information is more valuable now in business than it's ever been.