AFAIK, all US visa grants are at the discretion of the officer reviewing your case. Anything that strengthens your case in their eyes can only help. However, I doubt they'll stamp visas where the criteria aren't met (which, according to the OP, he did, so that sucks).
Yes, that's what they told me, you must meet certain requirements and also the officer has to be convinced that your visa will bring something good to the US.
So it's the requirements + strong proof that you will create jobs in the US or your are a great scientist, artist, etc... or you have a lot of money to invest.
