It's the same thing as cable and whatever else. I'm feel like I'm constantly canceling services and restarting them to get the better deals (when the threat to do so isn't good enough). If you're willing to go through the hassle of creating new amazon accounts, or whatever it may be, to get the perk, the others are subsidizing you.
I am not sure it makes me happy either.
In any case, I am a bit sad I no longer apply to the free tier.
It's the same feeling you have when you see your mobile provider has great offers, as long as you are a first time buyer or if you are switching providers. But existing users... not so much.
I know what the end goal is for Amazon, but in the mean time I've just paid last month about $250 to reserve an instance for an year while new users get two micro instances for free.