In part because of the lawsuits from the late 1970's, the NCAA left autonomy for major college football with the schools that wanted to pursue it (Big 10, SEC, SWC, Big 8, etc.). They split division 1 (for football only) into 1A & 1AA (later FBS & FCS). The C in FCS stands for championship as the winner of this tournament each year is the NCAA D1 football champion (although the world recognizes the top FBS school as champion).
At the time broadcast revenues were substantially smaller than what they have become. As the NCAA doesn't control FBS football, they cannot extract revenue from the product the way they do with all other sports and football at FCS and lower levels.
Outside of NCAA tournaments, broadcast revenues are earned by conferences and distributed to conference members (with exception of local radio and other minor items that most conferences allow individual schools to negotiate separately). This is where the P-4 gains it's largest advantage as the most lucrative product (FBS football) doesn't have to pass it's revenue through the NCAA.
We are decades beyond the point of being able to get the toothpaste back in the tube so to speak and the NCAA is petrified that the top 65+ schools will pack up and form their own intercollegiate athletic association, leaving the one legitimate revenue generating product (men's basketball tournament) as a second rate product as most of the best teams will be part of the new association's tournament to end each season.