Yesterday I always made sure to include banners and musicians within my units but are they a necessity? So long as you can get some sort of Stubborn model within a unit is it better to save the points on banners and musicians and just grind through units with spears and use the points saved to provide other units? Surely, the Cold-Blooded rule makes the absence of banners and musicians not such a silly thing to do, unless the unit you are up against causes Fear...
Banners are more important to Sauruses for their static CR bonus than their help with leadership. Still take them unless you have a very good other place to put the points.