Blizzard is (part of) a corporation. Corporations exist solely to make money. Taking money and giving it away without a profit-oriented reason is actually harming shareholders and can get a corporation into a lot of trouble.
This is why it doesn't make sense to criticize Blizzard for not being more "pure" about this. Absolutely they have some ulterior motives in producing a pet for charity and keeping half the proceeds. It does make people feel better about purchasing the pet, and might help increase sales. From a corporate point of view, just giving the money away without getting anything in return would be irresponsible.
This is how the world works. I agree with an earlier poster that the best way to describe this is win+win+win. Blizzard wins some more money, but the charity also wins a large donation and we get adorable pets.

Pamoya, I've worked for several companies, ranging from very small to Fortune 100. *ALL* of them engaged in some form of charitable giving. Sure, some of it came from employees, but the company frequently offered additional gifts, contribution matching, etc. In contrary to your comments, many corporations actually see charitable giving as a very important part of their overall image. Sure, they're not entirely altruistic - they know it gains them good-will among consumers, at the least. But I'd say it would be pretty rare for a company or its shareholders to get upset based solely on a charity campaign.

@Pamoya

once again, people make random claims that they think sound good, but have no bassis in reality

Any company with an acounting department worth its salt, makes mass donations yearly to offset tax. Now blizz would have made a charity donation to offset their income tax regardless of if the pet was for sale or not, they just get to advertise it now.

Giving away money to charity for the purpose of off-setting tax is in the best interest of the shareholders, thus your point is invalid

I would describe this as Win + Win + Lose

Blizz gets tax offsets and good publicity + only has to give away 25% of 48hrs worth of pets ales
Charity gets some money
Players pay for a pet

PS i'm not angry at them for being pure or not, i'm angry and all the blizz lovers who seem to be aplauding them for somthing they would have done anyways.

Its like going to work, doing what you get paid to do, and then wanting everyone to tell you how great you are for doing it.

I understand people are happy about the charity aspect, but blizzard would have donated a sizeable amount of money to charity anyway for tax reasons.

so, that leaves us with one logical conclusion, they only tied it into the pet sale for the image it would provide pet sales.