Check out FlyerTalk.com sometime and read the post histories of some of the manufactured spenders. They are some of the loudest at complaining about airline food, other passengers, not getting their upgrades to post, etc. These are people who pay pennies on the dollars (if that - see US Mint fiasco) for their tickets. They indirectly increase credit card fees for the rest of us and create a mountain of paperwork for cashiers and mangers at drug and grocery stores.
If other passengers are high on their priority list, I'm happy to admit I'm wrong and have misjudged the situation. I've not seen much evidence, either traveling or reading through FF sites/blogs, to suggest as much.
So you can actually tell who on the plane got there through apparently undeserved scamming, versus the "legitimate" users? Are you sure about that?
As someone who doesn't game or optimize these sorts of promotions, I have absolutely zero issue with those who do. Honestly, good for them.