I don't like ads myself, but then again, I would glady put up with the ads to not have to pay for something. I too wish it was mentioned before I downloaded the new version, but I understand why its there. People who upgrade should be told about it in advance so they can chose whether or not to upgrade, or perhaps they can be grandfathered and not required to show the ads.
Think of it this way. There are some countries in the world where there is no advertising on the air (TV). Either one of two things also exist in those countries: either the programming really really sucks, and/or everyone who owns a TV is required to pay an annual tax to pay for the TV stations. And I should also mention there is only a couple channels in those countries. In other words, someone has to pay for it. In most countries, the advertisers do, in other countries either they do without or they pay taxes to fund the TV stations. It's be nice if everything is free, but the money has to come from somewhere.
I too have several websites that takes up a quite a bit of my time, and sometimes I have to get creative to get the revenue flowing.
For projects that are making me money, I buy a license, but for sites that don't make money, or for small private sites that only a couple people will use for collaberation, I don't due to money constraints. (Once I get rich, I'll probably buy licenses for most sites since I will be able to afford it. Need to get rich first, though.

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If nothing else, you might get more paying customers because people want to remove the ads.