Minecraft seems to strike the right balance here. Authenticate players on public servers to avoid spoofing other accounts, but also allow people to run their own private servers and disable online mode. Granted this enables piracy but I'm sure it hasn't put a dent in their sales.
Even if it has put a dent in their sales, Notch doesn't seem to mind.
As much as I agree with the sentiment, it hasn't actually affected their sales. If consumers actually cared about it then there would have been far fewer sales and the servers wouldn't be overloaded in the first place!
No shit. And let's quit going along with the fiction that the online requirement was for any other purpose.