Ads have existed across mediums though, from print, to TV and now on the web. IMO they reflect a fundamental unwillingness of the general public to pay for information.
I think that for the majority, the issue isn't really the money, but the friction. Having to set up an account, or pull out a credit card, is an enormous friction point. The path of least resistance is to tolerate the ads.
A proper micropayment system could greatly reduce or eliminate the friction of payments, but we still don't really have one.
