Donations vs. Advertising - is clicking in our own self interest?

Many of you have already likely heard that Wikipedia is asking for $500,000 in donations in its year end fund drive. They have already raised $74,000 and are bringing in about $12,500 a day. No doubt contributors are thinking "I love this service, of course i'll donate, plus it's tax deductable." But why are people so willing to donate to wikipedia? And, on the flip-side of the content coin, why are so many people opposed to adds?

I have a sneaking suspiccion that a large part of the reason people donate so much to wikipedia is that they don't have advertising. Why is that? Why do we have good feelings towards sites that don't show us adds? Why do we have negative feelings towards sights showing adds, even when it is done tastefully and we really like what the add is selling?

People are willing to Donate their own money to wikipedia at a rate of about $.40 CPM (or $.004 per page view)* but they get offended by publishers saying, essentially, "click on this, it will cost you nothing but a few minutes and it is likely something you are already interested in and may want to buy" by putting up advertising.

We're willing to part with our own money to support a site we like via donations, but get offended at the proposal of taking money from advertisers and giving it to publishers when we see advertising.

I suppose that the optimal plea on a website would be something like a left column which says: "Like our site? Donate to us" and a paypal donate button followed by "Or, support us by visiting a sponsor if you see something that interests you." Based on the social norm of reciprocity, and what can be seen happening over at wikipedia, I think this would lead to an increadible increase in clickthroughs (if you haven't listened to The Power of Persuasion yet, you should - what I learned from that $2.95 and 1 hour will add a cool $3 or 4 million to my earnings in my life). Would this be against the adsense terms of service?

This also suggests an interesting self-interested action on websites we like. If it is a site whose content you value, and which doesn't throw offensive adds in your face, then it is in your best interest to briefly glance at the adds and click if there is something you find interesting. This is the exact opposite of what most experienced web readers do. We look past adds, parse them out, avoid them like the plague. Why? If we like the site, we can 'donate' for free by visiting a few sponsors. We can be "adsense patrons" of any site we like, and it doesn't cost us a dime.

NOTE: I am not asking you to click on my ads. I am only proposing, for discussion, that instead of parsing out ads, we should make an effort to look for them on sites we enjoy. Hypothetical argument, please don't throw me out of adsense. I couldn't live without that $.03 a day ($.04 on a good day).

* Wikipedia figures assume 1 million visits per day, 5 page views per visit, and $12,500 a day in donations. Stats from alexa.com, wikipedia.org, and metricsmarket.com.