Fox News has never been included in Flex. Flex doesn't have "all the news channels except Fox", only has CNN, you need to add the News package to get the other news channels. If you have locals added then you get the local news - but that costs extra as well.
Fox News is #1 so agree with your question about Fox News. Perhapes the reason is Fox News is conservative and Marxist PC person makes it harder and more money to receive Fox at Dish.
It is our contractual obligations to the channel owners that determine the channel line up in our packages and add-ons. It is the channel owners that tell us what package or add-on they want their channel to be in.