@Torque Tonight:
Errors are human nature. Say 1 in 1000 times you mishear, misunderstand, forget the clearance, but the guy in the other seat rectifies your error. This will be the 1 in 1000000 where both pilots missed the call (or lack of it) simultaneously...
Your argument makes sense and I'm in agreement with reducing distractions such as 121.5, especially where lesser ATCs feel constrained to issue incessant chatter as we pass 3 mile final.
However regarding the 1 in 1000000: caution is recommended when squaring probabilities - the resulting huge numbers can be misleading in post-incident analysis. It's not unlikely the other guy will miss the call too, not because of mere chance but due to the same environmental factors, distractions, impractical SOPs, groupthink, whatever, that are affecting you in the first place.
It's not meant a critique of your point to say that pilots should be vigilant about having to "take the blame" because of overly simple probability theory - the kind that the insurance company is most likely to deploy in its favour!
The
Sally Clark case offers salutary food for thought.