Did you experience the internet before ads? If not, you might be surprised by how rich the experience was.
I guess my point is things like Gmail, flickr, last.fm etc would struggle to exist on subscription only. Perhaps we can do without them all though?
Also, I agree with the poster below with regard to finding content these days, it can be tedious. A search on a subject can find pages of aggregators, e-commerce sites and little in the way of true content. I don't find this the norm, but it happens.