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.