I completely agree. When i first heard of the Preacher series, the Saint's origin was the first part that popped in my mind. I hoped they would make it exactly the same way.
Why they decided to change one of the best chapters of Preacher is a mistery.
Now I wouldn't be surprised if they changed the ending, too.

Then it won't be, because we'll never do.

So I suppose we won't see the frozen hell, Satan and the Angel of Death forging the two colts and the Saint's shot before leaving Hell?
That was the part I wanted to see the most in the series!