Is it really that important to track which banner campaign, which keyword, which add is generating the most traffic? Isn't the internet so well-balanced that you get what you pay for? Are there still loopholes and tactics to generate more traffic by paying less?

Please tell me if I'm totally missing the point here... why is this so important?

Hell yeah!!
If you're paying thousands of dollars a month and getting million of visitors, every penny, every CENT, counts (per add)! It's not so much about visitors, it's about targeted visitors that will actually buy your stuff. That's why paths and goals are so important. Will the visitors from your campaigns buy your stuff; are they TARGETED visitors!?

Why do you think Google and Microsoft are investing so much in their analytics tools?
They want to allow advertisers to optimize their ads, giving them more income, in turn giving them more to spend on their advertising network...

Indeed, if you don't invest in, or make money from your site, than all those options aren't that usefull.

Of course you wan to know if your dollar is well spent and if you could get more from that dollar..