Wow, 24 hours go by and my thread bloats into 7 pages of debate over ear training and its importance to education or composing.
So, now it's my turn to speak on the subject... because I have interesting thoughts on the topic - yes, they are absolutely interesting, without a doubt.
EAR TRAINING (Dooms-day music playing)
For the run-of-the-mill musician/composer/whatever, ear training can be beneficial.
For the music educator, I happen to believe ear training is a critical skill to have and be able to teach where appropriate and relevant.
After all, any student of mine should at least be given some methods from me on how to begin training their ear. They don't necessarily have to be good at it, but developing that skill will help them become a better, more capable, more independent performer. The student's ability to self-assess is important in education, and it's no different in music. For a composer, assessment is far more subjective. You either like or don't like what you've created, it either sounds right or sounds wrong depending upon what you want. For the performer, though, there is a "right" and a "wrong" note, a "right" or a "wrong" rhythm, a "right" or a "wrong" dynamic, etc.
So, that's how I see Ear Training being relevant. Shocking.
"Useful"? Yes. "Necessary" or "Essential"? Depends.