I, like some others on this thread, would not participate in anyone's plan to defraud the taxpayers. When my husband and I got married, we lost thousands in certain tax benefits immediately and we have paid a higher tax rate every year since. We joke about it, but there was never a chance that we would have pretended to be married without being legally married just to keep that money. We weren't entitled to it just because we had gotten used to it.
I see these situations as fraud and I don't think financial incentive makes fraud ok. I agree that it's simply gaming the system and that's not a victimless action.