This is very true. IMO PPC has two purposes. First is to get exposure for the site and clicks while you raise in the search rankings.
The second is once you've risen in the rankings, to supplement your natural results. If AdWords (and the other PPCs) are you major source of traffic, I'd suggest taking some of that money away from AdWords and paying for some SEO.
I think this is a very good point. From looking at my competition, and peole I know who do net ads, many people in internet marketing don't have degrees in marketing and advertising. A lot of advertisers seem to be webmasters or have other areas of expertise that also happen to do PPC as its a current web exposure trend.
This leads to a lot of people not understanding marketing who are forced to learn as they go, and hope they are getting it right.
It's a good thing we have a place like this to learn from each other to make the best of our ads and time possible.