I like the counter arguments that tend to fall into two camps.

First, it's "on the user", i.e. WP shouldn't be liable if someone abuses the tool. Actually, that's not entirely accurate. Napster had a legitimate tool for other use (P2P transfers), totally on the users to decide how to use it, right? Not so said the courts. Similar to the hammer example -- hammers are used for legitimate purposes in the main, but if you were a hammer manufacturer, and you made one end like a tomahawk to make it easier to kill someone but it had no "hammer-related use", chances are you might be an accomplice-before-the-fact (criminal) or contributorially negligent (civil). Guns may kill people, as the slogan goes, but it doesn't mean you have no liability if you hand out loaded guns to toddlers in a playground.

Second, it's like copy/paste or other tools available. The real question is the purpose of the tool -- to copy text from another site and put it in yours. On the face of it, it's wrong. It violates copyright. It may be a defense to say "I had permission" if you did, but it isn't a defense to say "well I could have copied it other ways too, it just happens I used Press This". Anymore than you could say, "Oh, well, I killed someone with a bomb I bought from Jack, but Jack has no responsibility because I could have shot or stabbed the person instead". Yep, you COULD have used copy and paste (Ctrl-c/ctrl-v) but that doesn't change the fact that you chose a tool that made your illegal activity easier. If you build the tool, you have some responsibility for how it is used if the use is a direct foreseeable consequence of the design (i.e. Napster, ThePirateBay, etc.)

Ultimately, I don't anyone is saying the user isn't primarily responsible. They obviously are, even if we don't start with that premise as we all should, or express it openly in our posts. The real question most of us were talking about was what comes after that, i.e. "what does this mean for WordPress?"

For me, there are two issues:

a. On a legal basis, there is an admittedly weak argument to say that WordPress by including Press This would attract any liability for someone using it to pirate. While it's not zero chance, it's probably not that high. We can dance on the head of a pin as we have, but it's likely hypothetical.

b. On an ethical and far more practical basis, there is a much stronger argument in my opinion to say "You've created a tool that facilitates millions of people to create and post original online content on the web" (that is by its nature copyrighted unless released otherwise) yet at the same time "You've created another tool within that tool that undermines the entire community's ability to control their content and protect it from poachers".

Sure, anyone could use a plug-in instead, and people wouldn't likely rise up in revolution to block it, but should such a potentially-community-harming tool really be part of the core?

PolyWogg