MNF never would have had the ratings it did without Cosell’s personality to drive viewership. Lots of people who had the same reaction to him as you did actually watched because of him. In other words, they loved to hate him. Tuesday water cooler talk was as likely to be about Cosell as it was about the game itself.
I agree with you, but for me as a kid, Cosell was merely an annoyance. I loved football, period.