Big +1 to the live solos are boring posts! I think electric bass [i]can[/i] have just as valid a coice for expressive solo performance, but finding a player who can put all the pieces together is a real needle in a haystack affair. I was listening to some Marcus Miller tonight and I genuinely enjoyed his playing and musicianship.
All the usual suspects (Jaco, Flea) etc... are superb musicians who just happen to have chosen the bass guitar as the tool of their trade. Players like these can stop an audience in their tracks at 20 paces. Expressive soloing transcends simply repeating charlie Parker/Jaco licks over the changes and enters the realm of communicating emotional content through sound. THAT, my friends, is a tall order.
It's like stepping up to the microphone without knowing exactly what you want to say, and that can only end in embarrasment and airborne fruit.