That still would ignore major sources of pollutants, such as tires (that get distributed into the air and on the road while driving). Electric cars do not improve that at all. If we just focus on emissions from the motors, why can't we just replace the motors instead of producing new seats, steering wheels and doors, while attaching a bunch of computers to it that also undermine the driver's privacy, and selling the package for double the price?

A yeah 100%. You couldn't replace an ICE with an electric motor, at least not with current technology, but you could definitely replace it with a more efficient one. Maybe even with a hybrid if you're willing to give up some room.