If the spectrum is otherwise used for cancers like advertising then I wouldn't consider interfering with it to be a bad thing.
In addition, I don't think these "pirate" operators have any nefarious intentions and wouldn't wish to actually interfere with any station (as it would be counter-productive to their own listeners, since the existing station would scramble their own broadcasts too) so I am not sure this has ever been a real problem.
How much space is going unused? I vaguely remember something back in 2013 about nonprofit groups having a small window to apply for community FM radio stations. But I assume there hasn't been a window since then.
Is that because there's no availability left anymore? Because radio stations don't want competition? Because it'd take an act of Congress and Congress isn't doing anything anytime soon? I genuinely have no idea.
I'd be more or less sympathetic to pirate radio based on the fairness of the legal avenues available. (And clearly I don't know much about those processes.)
They completely fail to mention that spectrum is limited and that you are probably causing interface for someone else.
The right thing to do would be to give them free or subsided licenses.