But junk is perjorative word which suggests that it is entirely disposable even desirable to remove. That may turn out to be true but the experiment required to prove that thesis would require closely observing a biological systems evolution and disease evolution for some length of time, with "junk" DNA somehow removed and repressed. It may turn out to be a sort of filler with certain characteristics that work out to have repercussions for longer term genetic dynamics, and it may not. Since we cant tell yet, the name for it is very presumptive.