Why is Wikipedia worth donating to?

Probably because they don't realize what they're losing, and indeed what the internet and all of world culture is losing, with the decline and eventual elimination of professional reference publishing.

Moreover, they probably don't know what happens to the money - for a large chunk of it, absolutely nothing. It just gets put into a savings account. What money is spent goes mostly to Wikimedia Foundation salaries, rent, and "outreach programs" which are little more than spurious pie-in-the-sky promotional activities. To be sure, some of it does go to actual server maintenance and data center expansion, as well as bandwidth costs - but that's less than 30 percent of their annual budget, and that percentage drops every year.

Most of the MediaWiki developers, as well as nearly all the people who actually write and maintain the articles (as well as try to prevent ongoing "vandalism") are volunteers who will never see a dime of the money that's donated to the Foundation. If you care about quality and accuracy, there is quite literally nothing you can do to promote that on Wikipedia short of doing the work yourself, which unfortunately is the worst thing you can possibly do in terms of maintaining your sanity.

Wikipedia is steadily creating a kind of "monoculture" of general-reference information on the internet. There are thousands of "scraper" sites that exist simply to mirror Wikipedia's content to improve their search-engine rankings... Just as the Microsoft Windows OS monoculture makes it easier for viruses to propagate through the global network, Wikipedia makes it easy for inaccuracies and untruths to spread everywhere, into places where they either can't or won't be fixed, in some cases ever. Meanwhile, Wikipedia's effect on opinion and scholarship diversity throughout the internet is similar to Wal-Mart's effect on product diversity throughout the economy - it creates a race to the bottom, destroying smarter and higher-quality ideas and web projects in its wake.

Other than that, it's not so bad, I guess...?

Wikipedia has more articles than any other online encyclopedia. Despite what some people say it is as accurate as other encyclopedias. Sure there can be vandalism on it but it's usually up for a few seconds before it's taken down. Sometimes I try to insert fake information into articles. Years ago some of the bad information would stay up for months. Now it doesn't last a minute. They've gotten really good about it. Also, other online encyclopedia's cost a decent amount of money so I'd rather just donate a few bucks to wikipedia since I've gotten well more than a few dollars worth of value from it.

Wikipedia needs money to "protect and sustain" it. Otherwise, Wikipedia editors would have to pay to edit and couldn't use the information at Wikipedia whatever they want. The editors would be very limited in sharing knowledge and wouldn't be very welcoming to new users.

Wikipedia was created by its founder as advertising-free medium, accessible at no cost. Thousands of writers shared his vision and developed the world’s most popular reference website. Many donated money to finance costs of hosting and operating a site with over 400,000 visitors per month.

However, many people, including me and my colleagues at WikipediaExperts.com , believe that relying on the “writing-for-free and no-ad-revenues” model is not optimal for further growth of Wikipedia. For example, would we have easier searchable Internet if, instead of relying on $23 Billion dollars of annual revenues, Google would adorn every search page with Sergey Brin’s picture and his “personal appeal” to donate?!

Still, Wikimedia Foundation, the organization which runs Wikipedia, has the right to choose the operational model and they seem to be determinate to operate on donations only. Thus all Wikipedia users who benefited from the site have to decide whether to donate money for covering Wikipedia’s operational costs. Despite my opinion that donations is not the best way strategically, I respect the work done by Mr. Wales, the Foundation, and the Wikipedians, donated to Wikipedia on various occasions and urge other Wikipedia users to do the same.

The only thing I can think of is because Wikipedia is very informative.

Yes! In reality, it is extremely primary for AB blood varieties to donate. It is correct that donors with AB can simplest donate purple blood cells to different humans with AB blood, however with plasma the crisis is reversed. To quote the American Red Cross: "Type AB plasma is common which means that your plasma will also be bought by means of someone, without reference to their blood style."