Coil on plug is just a natural evolution once you have multi-port fuel injection. The computer already has the ability to run COP so why not use it. COP solves a bunch of issues but it does create a few more. The OEM's have all gone to COP to get rid of the mechanical distributor and to get rid of long spark plug wires. On a race engine COP is nice since it allows you to adjust the timing for each cylinder. Also, really high HP engines need either COP or a mag in order to have enough energy to fire the coils.