Hal Bradley was once asked if he could read music. He replied, “Not enough that it hurts my playing!” However, I completely agree with you. It’s important to be able to understand the musical concepts, particularly playing lead that moves with the chord changes. Sometimes hanging on the relative six isn’t going to cut it. I teach music for kids here in the okc area, and some have made it far enough to start learning basic improvisation. I keep it simple moving through easy changes, but it’s important to me that my students are a step above the player that just hangs on the minor scale through all the changes.