They control the one absolutely essential element, a role not exactly obvious to everybody. This pleases them a great deal. Playing bass requires a peculiar personality. You can generalize about it with less danger than most generalizations. Despite the occasional grandstander, they are team players who flourish in the background.
Bassists are less competitive than other instrumentalists.
Listeners go to the bathroom during a bass solo. And there has to be some masochism somewhere in anybody willing to lug that coffin around. Constructing their central bridge between melody, harmony and rhythm, they are by necessity involved with totality. They control the music. Dave Holland controls it with more intelligence, power, variety and modesty than most.