It wasn't just some unlucky team working that went down the wrong path and produced a substandard product (Aperture or MobileMe), this was the outright replacement of a product that almost all iPhone users consider a core feature of their device and, at some point during their time with the device, depend on to help them in a confusing situation.
Then again, this whole discussion could be related to the fact that Apple users are about 985% more likely to nitpick a product than any other group of people on earth.
Or just that it was vastly wrong in a lot of places that weren't San Francisco. It was missing one of the two major train stations in Sydney for crying out loud.
I'm know there were problems with maps, but a lot of the teeth gnashing was/is exaggerated drama. Google routinely places silly things at the corner of Van Ness and Market, because it has no idea where they belong -- you just don't hear about it because nobody nitpicks Google Maps the way they did Apple's launch.