Not everyone who is getting the loan/rebate/whatever is irresponsible.
I was a single mom for many years, living in a teensy apartment and saving every last dime for a future. I had many people offer to help me "get a house" with a piggyback loan, etc., but I held true to my gut which was screaming "No". For a time I lived with my sister, but by the time I was in good enough financial shape to buy my own home, the housing here in Florida was over the top expensive, driven up by the market that now sees people in foreclosure because they used their homes as ATMs, or because they were put into a house that someone should have known was not affordable.
This year, through our diligence and planning and saving, we were able to get an FHA loan for a home I never imagined I could have. It is a fixer upper and needs some work, but we bought in a good neighborhood for almost half of what we would have paid three years ago.
The $7500 I am getting back will go toward needed repairs and extra principle payments. I do feel the frustration of those that bought responsibly years ago, but not all recent home buyers are irresponsible. I would gladly pay the money back, but it would be wonderful for me and my family if I did not have to do so.
Whether you made the cutoff or just missed it,
this is a GREAT deal. 
We've all experienced that sinking feeling in our stomachs
when we bought things on sale at a "great price" --- only to see
the very same items somewhere else 30% cheaper. So we make
the best deal we can as the opportunities present themselves to us.
The most important thing is that we honor our agreements, which is
something the major banks and Wall Street have gone out of their way
to avoid. 
But like UpUpUp pointed out, the only portion I don't like
is that the tax credit can be used as a downpayment.
I believe someone should qualify for a mortgage, get approved
for a mortgage and go to closing for that mortgage. THEN
you should get the tax credit...not before. I also like the
fact that the credit doesn't need to be paid back as long
as you stay in the home for 3 years. This will promote
neighborhood stability, price stability and future appreciation.
So like I said, anyway you slice it this is a good thing.
It is targeted help at the very industry that caused the
problem in the first place. To me, that's money well invested.
CanDo
"The right attitude is everything"