If (when?) I eventually move over to a more fitness/bodybuilder approach I'll use the pump in combination with weight progression in my workouts. For example if I know I did 90lbs x 8 in the curl last week and I'm aiming for 95lbs x 8 this week, that's progression. BUT after I've done the 95lbs x 8 my biceps feel fine and my front delts are tired and pumped then I know I did something wrong.
In that sense the pump isn't necessarily the most important part of the workout, but it's certainly a decent indicator that what you're doing isn't just moving a weight from A to B.
But hey, what do I know.