Heck, why stop there? Why not instant replay?
One, its not an American sport and we have traditionally liked playing our own.
Two, there are ties in the game and Americans hate ties. Do you remember all the handwringing that used to go in in college football before they had overtime? Hell, they even incorporated an overtime in hockey.
Three, Americans are now supposed to only like high scoring sports. A 2-1 baseball "pitchers duel" is now a thing of the past with juiced balls and pee-wee ball parks where the fences are moved in. In basketball, a 24 second shot clock was installed and a "no zone" rule was put into place just so nobody could play defense. They even seriously discussed having the "no zone" rule in football because they thought the scoring was too low, but they changed the kicking and passing rules instead to encourage higher scores.