I disagree. If I find someone consistently annoying, I would prefer to be able to put him or her on ignore, instead of getting so irritated I want to stop visiting the forum. Especially when the person in question only posts useless spam or other stuff that's not really of value in regards to content.
Furthermore, that everybody is entitled to their opinion does not, IMO, mean that anyone should be forced to listen to everybody else's opinion. And that a feature exists doesn't mean you have to use it.
Plus, I also thought it would suit some people who might want to put ME on ignore. :twisted: