Hy parksman, yes there is a very good reason not to eliminate the rear axle flexible line, the rear axle does move up and down and it can twist side to side. There is one quote from a GM engineer that I learned many years ago that I always quote to people when they want to change the factory design "parts left out cost nothing, and cause no service problems" so if there is something on your vehicle it is there for a reason. I always try to follow the factory design unless something more efficient/safer has come along since the original design, hope that helps.
