I’ve now read two novel attempts to explain the existence of junk DNA. To a lot of people, the very idea of junk DNA is offensive: whatever process built us, whether divine fiat or the razor-sharp honing of natural selection, must be powerful, omnipotent or nearly so, and incapable of tolerating any noise or sloppiness, especially not to the degree seen in the eukaryotic genome. There is no room for error in design.
There’s also a strong whiff of human exceptionalism. Look at us, we’re pretty much perfect! Or at least, movie stars and super-models are the pinnacle of creation/evolution. How can you even look at Scarlett Johansson or George Clooney and suggest that they are built of monkey bits and lizard leftovers, or that their manufacture was in any way slapdash?
So there’s an amazing fringe literature out there reaching desperately to find some excuse to justify every scrap of DNA, and especially every bit of human DNA, as purposeful. It sometimes gets weird.