Probably because not everyone is aware of the issue. If you know how E Ink is supposed to look like (no color blotches), then of course you can say something is wrong with your device. But if you are new to e-book reading, and if the Kindle is your first device, well, some people may not know the difference.
That said, I am perfectly happy with my PW, despite its defects. There are too many things in life that aren't perfect - I have no room to be upset about my e-book reader.