They became required because a dad backed over and killed his own son. That father fought for years to make them required so no one would have to go through the same pain he went through. Why would you not want one? You could not look at it if you don’t like it. But it’s one of the best possible safety features imo, and it’s dirt cheap compared to the cost of a car.
It’s just another tool. You wouldn’t only look in your passenger side mirror just because you have one. Use it along with all your other tools. Most standard cars have 3 mirrors and a backup camera. Most drivers also have necks they can turn.