So? I learned by ear initially, and still have a good ear nearly 60 years later. But being able to read music - which I taught myself - is a bonus.

I downloaded the sheet music for "Puttin' On The Ritz" the other day. I'm perfectly capable of working it out for myself but - sometimes - it's useful to see what the composer (Irving Berlin in this case) originally intended. And very interesting it was.

So whether it's "important" or not - whatever that means - is purely subjective.