If you had read the link to the source information, you would have noticed that Blizzard does not condone donations to developers, only fee-based add-ons and solicitations for donations in-game. I don't use add-ons that require a fee, and I use some pretty sophisticated add-ons. I do donate to developers of add-ons that require constant maintenance and whom regularly produce excellent products, and I don't think that this will change.

I don't think it's unreasonable for Blizzard to be the only ones to profit off of their product.