I have to disagree. With regards to your first point, I have been publishing a free newsletter about the stock market since August, 1996. For almost a year it was ad free. Way back then there were not that many ads in ezines. When I started carrying one sponsor's ad per issue, no one complained.
Most reasonable people realize that viable ongoing organizations have to bring in revenue.
But it can effectively be used in conjunction with carrying one or two sponsor ads. I know because that is exactly what I do. If you have good content on your site that you are driving them back to, having an ad in your newsletter is not going to slow them down. With the mail list feeding traffic into the site like this I feel that one has to ask themselves which is more important, advertising through the list or using the list to generate traffic in the site. Most would answer money or freedom from the rat race.