They are the headliners. Often it is the musician at the front of the stage, as well as the piece he or she has chosen to perform, that helps ticket sales. The overwhelming majority of my experiences with soloists has been fine. However, once in a while someone comes along with ideas so far away from what I envision that I have to refrain from going to battle.
Who has the say in these instances? Well, the soloist has practiced any given piece much more than the conductor has studied it. This raises another issue that seems more common today. As with many orchestras, we are at a time when many of our stars simply sound very much like each other. On the other hand, some go to extremes, sometimes just to be different.
What do you think the relationship between soloist and conductor should be? What happens when they truly disagree? And is the art of collaboration becoming obsolete due to the sameness of approach to any given work? Let me know your thoughts.