Are online subscriptions hurting the New York Times? Many news sites on the web are free. CNN is free. There are thousands of reliable blogs (hint hint this) and they are mostly 100% free. Why do they not stick with the ad supported model?
I think that it honestly puts them at a competitive disadvantage. By making readers pay for content that they could find free elsewhere they are effectively killing themselves, like lysosomes they are breaking down their own company. An ad supported solution may bring less revenue in the immediate future but this current system will kill them. The Boston Globe has the same system.
So why do they have it? They are afraid of change. They have used the subscription model for 400 years and they are afraid to change. Change is a-coming in publishing whether they like it or not. It is up to them to adapt or fall.