I think broadband killed them. Or lots of bad decisions by the big people at the top.
Another possibility is the huge amount they spent in sending people diskettes and later CDs, with their bloated install files.
And the passwords - they always cracked me up!
Now I know - AOL is not dead yet. Some of my friends still use AOL addresses for their email. But my point is this: they are a slim shadow of the giant they once were.