From the perspective of liking my software free and open-source, I was actually a little excited about this announcement when I first heard it. And then I started thinking about all the implications.
I've been a fan of QuestHelper for quite awhile now, and I never saw a donation "reminder". And I didn't get it through WoWMatrix either, I downloaded it straight off WoWInterface manually, every time it was updated. I think it's a shame that Zorba is being forced to mothball that project due to this. The inability to even have the chance to pay my favorite mod authors to keep addons I like functioning is a mistake, IMO.
Another good addon that they've killed with this announcement is nUI. This is the Mazzle of 3.0, but instead of a collection of addons automatically configured, Scott has written an entire UI to replace the default. If I weren't so addicted to many of my addons that don't mesh with his, I'd use his in a heartbeat, it's very very nice. But he's been out of work for awhile as I understand it, and now that he can't have a seperate free and premium version, he's said it may not be worth his time anymore to continue development on. This one, I beleive, is truly tragic.
Last of all, I just noticed Mundocani taking down his postings of GroupCalendar and Outfitter from all the hosting websites. He doesn't even ask for donations as far as I can recall, but he's done that in protest. I don't disagree with him either, but I do regret the loss of such talent from the UI Dev pool.
Blizzard is not making any of their fans love them for this, and I sincerely hope they reverse this policy.