Flanderization/Oral Tradition

Gods originally portrayed as Chaotic Neutral or even mostly good are frequently reinterpreted as evil by competing sects/religions historically. Modern media does the same and removes the character flaws of "good" gods in retellings of mythology in order to simplify them, making them fit modern good/evil dichotomies better.
- Virtually every mythology in modern day media is subject to the latter. Hades and Set are victims of the former: the Greek god of the Underworld is frequently interpreted as the villain of the Greek pantheon when in fact he was feared but never unjust, while the Egyptian god of chaos and some aspects of death apparently became evil rather than a scary enforcer for good due to Egyptian religious political wars.
In the old polytheistic days, gods weren't characters in anthologies, they were everyday gods that you'd pray to when you needed something, or just as part of your daily ritual. So when you'd hear "Zeus," your first thought would be "king of gods, god of hospitality, law, civilization," not "Depraved Bisexual who'll do Anything That Moves in Whatever Shape He Likes." Similarly, "Hera" would inspire "goddess and protectress of women, home, family, and domestic life" not "Clingy Jealous Goddess in Sheep's Clothing." However, because now all that we have left of these gods are the stories they left behind (and what stories!), we tend to picture pretty much all gods as caricatures of their original selves.