The reason a Firefox package wasn't included in Debian? The icons. That's right, the Debian guys didn't like the licensing for the icons included with Firefox, so they didn't include it. Instead, they created their own icons for Firefox, called it Iceweasel, and included that. Other than that, Iceweasel differed from Firefox in no way whatsoever.

The moral of this story? Debian developers are petty and stupid. They also enjoy shooting themselves in the foot.

People will never understand Debian because of the Debian Social Contract, that there's a whole lot more involved outside of a simple programming point of view.