Your pump motor is connected to electricity there is a metal shaft from the motor that runs right into the water circulating in your pool. Line of sight and distance aside that metal shaft in contact with your pool water can and will put potentially deadly voltage and current into your pool water.
The bonding loop in your pool prevents there being a voltage difference between all the elements in and around your pool. Without a voltage difference there can be no flow of current which keeps adults and kids from getting hurt.
TLDR : connect the bonding wire so nobody gets hurt by accident.