Eric Ripert's approach is essentially that if the cooking liquid tastes good, it will help impart flavor on whatever you cook in that liquid.
By adding ham & aromatics, the goal is that the octopus will take on some of that flavor. By converse, the same theory would say that if you cook in a simpler, bland water, your octopus will flavor the water, and the water will dilute the octopus's flavor.
Whether it's necessary is really a point of personal preference. You may find that other ingredients in your recipe provide enough flavor that you can go with the simpler method, or you may find that it really needs that extra flavor.
In general, these seemingly complicated, seemingly unnecessary steps (like using broth instead of water) make restaurant dishes have a more complex, deeper taste. Sometimes that attention to detail is just the difference between a home cook and professional chef. Sometimes the difference can be subtle and feel "not worth it" when cooking at home--you'll have to decide that on your own.