They're also extraordinarily harrowing. If you ever do read the transcripts, try and imagine them taking place between two or more pilots trying to deal with a deadly situation for themselves and their passengers. While accompanied by the background noise of violent maneuvering, alarms or engines screaming or indeed engines on fire or exploding. Or in really bad cases, hijackers yelling commands. Or if things are really bad, all of the above. And then often finishing with the sound of a plane impacting the ground, cutting off suddenly and being replaced by an ominous silence. I personally would not want to hear such a recording.
I've seen a transcript which ends with one of the pilots yelling "I love you mom!" just before their plane hits the ground, killing everyone on board...
Finally on a more practical note, pilots use a lot of jargon and abbreviations, some of which is specific to the model of aircraft being flown. If you don't know what a flight level is, or what ATC or approach are, or which check-list they're talking about, then they can sound and read like gibberish. And that's assuming they're speaking English. Flight crews talk in their native tongues whilst flying and not talking on the radio. So for example a recording from an Air France flight would be largely in French.