I'm not sure why.
Anyone who reads and believes Romans 1, for example,
shouldn't have any trouble with the fact that what was experienced in the Garden was passed on to all men.
The knowledge of good and evil, the choice to do evil and reject doing good ( unless it suits us to not reject it ), and many other details are all in the Bible.
"Gloomy" it may be, but believers have been rescued from it.
They can pin their hopes on the fact that God saved a people
from themselves,
to Himself.
Many today try to downplay Romans 1, Romans 3, Psalms 10, Psalms 14, John 3:19-20 and
many others...
All in favor of a God that loves everyone and doesn't want anyone to perish.
As I see it, that will sell a lot of airplay and get rave reviews...
But the fact of the matter is, the bad news is very bad...
Which makes the Good News
really good.