You know what I hate? I hate when you go to the supermarket one week, and you can shop quickly because you know where everything is, and then they next week, you go back and the store has rearranged everything. I know why supermarkets do it. They want you to find new products while you're hunting for your regular ones.
I don't know why Google would do that, though. Favicons are part of brand recognition. Ever picked up something with new packaging and it say something like "Same thing – new package". Well, that's just fine, you now know to look for the new package when you're at the grocery store, of course, after they moved everything again. Favicons oh the other hand, are in your browser's tab bar, or in the bookmark/favorites list. They're small, and they don't have anything that says, "same thing – new package". It's confusing for users.
Here's Google's old image
And here's the new one
I like the old one better because it's more colorful, and easier to see. The new one just looks like a little blob of blue.