The OP mentioned Entwistle and Squire as examples of virtuosos who were doing it right. I agree. They played busily, but did it all within the context of the song, acknowledging the melody at all times. They were playing complex counterpoint that enhanced whatever the other instruments were doing, as opposed to merely using the song as a backdrop and soloing over the top of it. I think of it as playing "inside" the song opposed to "outside". Does that make sense?