It's not just common sense, it's peoples' behaviour online. Most people don't pay for services online.
Most online newspapers such as the Irish Times that were subscription-based are advertising-based now because no one would pay the subs.
iTunes is successful but pales compared to illegal downloads.
On average only 20 tunes on an iPod are from iTune.
http://news.bbc.co.uk/2/hi/technology/5350258.stm
There is a select group of people who will pay online for intangibles but compared to the once huge record buying public it is insignificant.
ok so the current system doesn't work. Are you willing to give another system a try........ say....... people donating monehy to artists they are fans of?
I'm not saying it's a solution to all the problems but it certainly shouldn't be thrown away based on 'common sense' or a figures relating to a different system