I HATE the idea of a forced fee, and if one is instituted, I will reduce my donation correspondingly; however, I only say that knowing that other people are freeloading. I am running 180GHs - I've been on this pool for over a year now, and I've given the entire time, even when my sweaty little GPUs were struggling to break 1MHs before the ocean of asics hit.
I feel pretty much the opposite. If you want (or need) to be paid, charge a fee. If you don't, then you don't need my donation.
At least that's how I feel about services such as this, where it's really simple to charge a fee to the people who benefit from the services. It's not like Eligius provides a service where freeriding can't easily be prevented.
You're basically right. But hasn't it also got to do with idealism and the believe that people who share your ideas probably also will support you?