As a professional, is it not your responsibility to deal with the conditions and recognize issues such as fatique? This is the same for any high risk profession.
OK, so you're half an hour from landing, you realise you're dog-tired, you're not in a position to stop. Sure, you can try to double-check everything from then on, but that just slows everything down, including the thought processes and decision-making. They were on final, realised something wasn't quite right but failed to understand exactly what, so they called ATC and found a solid piece of cheese as a result.
In the absence of the CVR and with a consistent story from the pilots, that's probably about the best you'll get. NTSB has come up with a good reconstruction of what happened, but 'why' is going to take a lot longer and may never yield a verifiable answer.