I equate musicianship to any other form of education. There are "street smarts" and "book learning" Both are viable and noteworthy (No pun) and each has a distinct advantage. It is very possible to achieve high levels of success playing only "by ear" but in order to be really complete as a musician ... you need to read as well. It's just like learning to talk. Babies learn to talk without reading, and that's OK for a while, but in order to take it to the next level, it's important to learn to read so you can broaden the scope of your knowledge with the experiences of others.

In the practical world of music performance - I'd rather play with a cat that has soul and feeling rather than just theory and technical training anyday. There is only so much the books can teach you, and then it's up to the player to make the notes their own. There are many people that have studied, and peaked early on and they will never develop "soul" or ever know the real meaning of how to "swing." These are things that have to be FELT. You can't teach these skills, and no books can even come close to showing you how. You either HAVE it or you DON'T. (hard truth?)

Music exists on the page, AND in the heart. It's a beautiful combination of form and fashion, and you should treat yourself to the entire experience.

I could read fly paper in college, but these days .... my performances are almost all done exclusively by ear. Even when I learn new material - I just sit down with the CD and start picking out notes till I get it.

Don't debate the validity of the two playing methods - they are both VERY real. Learn both, and you will be that much more complete as a musician.