Am I misinterpeting the case for humility? Maybe the point of humility isn't better communication, but better understanding. It's hard to learn if you think you already know everything.
This sounds good. But if your goal is better understanding, your main injunction should be "Overcome bias," not "Be humble." Learning how to apply the principles of Bayesian reasoning will do a lot more for your understanding than eating daily helpings of humble pie.
Admittedly, overestimating your own abilities is one source of bias. But (a) it's far from the only source of bias, and (b) it's not clear how you should adjust your beliefs to compensate for it. After all, other people overestimate themselves too, so it doesn't make sense to naively move your beliefs closer to theirs.
In contrast, studying other sources of bias often gives you specific advice about how to get closer to the truth. For example, research on availability bias tells us to put more weight on averages and less weight on vivid anecdotes. Research on selection bias similarly tells us to put more weight on random samples and less weight on purely observational methods. If you really want to improve your understanding, telling yourself "I'm not as good as I think" isn't very helpful. It's far more productive to study specific errors and stop making them. And you'll feel better about yourself, too!