HCGirl10
I agree with highhopes. For me, ECs are very important to my application story because I don't have much experience managing people or leading teams at work, where I'm the most junior person. They allow me to show a different kind of leadership than I can show through my professional experiences.
Regardless of the nature of your work experience, I think it's important to show some sort of involvement to show you're multidimensional and have impact in your community as well as your workplace. But the extent of that involvement doesn't necessarily have to be that great, particularly if you're in a job where you're working very long hours or traveling extensively.
1000% agree. I think ECs give you some critical leadership experiences that you may miss out by virtue of being a junior person. I've been incredibly lucky to have some great leadership experiences at work and EC wise. Sometimes, I've felt I've gotten more responsibility at work, because my supervisors were aware of the amount of EC stuff I've done (especially within the company's junior employee forum).
Plus, it really does fulfill you and gives you a reason to get up in the morning

They also make you strive for balance---and that is incredibly critical, especially as a bschool student.