All right, I have read this post, and understand what both arguments are trying to convey.
First of all from a credit card point of view, they are not loosing money on this at all. All cards charge a percentage of the purchase to the company that you used to card to as a user fee.
For example, in my market, two years ago when I had a point of sale terminal for my business, Amex charged 7.3%, MC charged(for the premium cards, which is all reward cards) 5.3% and Visa premium card were 5.6%. If the average reward is 1-2% then as you can see they are charging a higher fee then the reward given. The do not care if you churn, because the have collected enough of a fee to break even on the higher rewards for the first bit.
No on to the other point, I agree that this is completely ethical, the companies have this built into their expenses, and count on many people charging most, but not all of the amount to get the bonus, therefore, it is a non issue. I do not agree with churning from a environmental point of view, however. Consumers, who are not mustachian, will but stuff to get the rewards, I will give them the benefit of being able to pay cash right after purchase(even though we know that many cannot, and end up paying interest on these cards.) the problem is they bought stuff, a new TV, a new DVD/Bluray Player, even a trip to somewhere nice. This is killing the environment, and that is my issue. For some of us to pay their mortgage in order to get the rewards, if your mortgage company is willing to pay the charges, ok.... but to just buy stuff is fucking the world over big time.