And ... I don't think there is any moral or otherwise requirement about responding. We are all here voluntarily! If you don't like a response - you can reply or ignore it. If it's over the top - you can report it. Otherwise, it should be everybody's choice to respond or not.
There is the right answer.
When we post up, we're offering a comment in the forum. Nobody, it seems to me, has an obligation to reply, even if I posted to them. Many obligations and time commitments can intervene. I don't think anyone should take it amiss if someone they've posted to doesn't reply.
If they're still posting up, however, some acknowledgment would be nice. But nobody owes me a reply to my 200-word monograph on whether Abraham Lincoln was justified in suspending habeas corpus, or Randy Weaver was obliged to show up for his court date after being entrapped by ATF. I may have opinions that are so advanced, so dazzling, that they may simply stun all the other Freepers into silent awe and admiration; so I can't expect any response right away, and maybe at all! ;^D
Help! I've looked in vain for the Ignore Reply link; where is it?