Let's say the tapes in question are only of dead guys, only concerning dead guys.

Why are these withheld from public consumption?

Meanwhile, every single Nixon tape has been publicly released, as have almost all candidly taped conversations by LBJ, JFK, Eisenhower, and FDR.

If they can release tapes of Presidents - even ones involving hallowed figures and harming their legacies- Nixon talking say about blacks badly with Billy Graham on the line -

Why can't they release wiretaps of Carlo, if there are any, Paul, Sammy the Bull, other guys from other Families?

ONLY reason is they possibly where not signed off by a judge.

Therefore, an illegal wiretap that led to a conviction entitles a redo or possible compensation for surviving family.

Just my assumption.

The demand isn't strong enough. Heaps of people want to hear tapes of presidents so they are released, transcribed and published. Not that many people want to hear Tony Ducks in the Jaguar or even Castellano is his kitchen. But when it's a famous mobster, the demand is stronger so they get released:
https://www.amazon.com/Gotti-Tapes-Sammy-Bull-Gravano-ebook/dp/B0083L10J8

I don't think anyone's refusing to release these tapes, it's just that the public isn't demanding to hear them and no one would make any money publishing them.