Although I am late in responding to your questions (I was out of town in a conference), I hope it is not too late.
I’d like to focus on the ad hominem attacks on Quintilian because I think often times some of us may become desensitized to the usage of words that are inappropriate and which lower value to one’s argument. Name calling and in Ramus’ case using terms such as “ignorant,” “stupid,” and “inexperience” among others, disappoint me as they drive me away from his actual arguments. I think that quite often attacks to one’s character is done on purpose to distract the readers or the audience from the real issues being presented. This may be the case of Ramus; I am not sure. What I do feel certain of is that depending on the audience using ad-hominem fallacies is indeed effective. Let’s take the case of John Edwards, for example. After admitting his affair with one of his ex-assistants (while his wife battle breast cancer), Edwards was condemned by many reporters and colleagues who called him inmoral, a deceiver, and all kinds of other words. Most recently, Edwards has admitted to be the father of his ex-assistant’s son (or daughter, not sure). Once again news media and tabloids have portrayed him as a horrible person. Many will question whether he is more horrible than Bill Clinton, who also went outside his marriage, or George Bush, who despite his immoral reasons to go to war got re-elected for a second term in his presidency. There is no way that Edwards will ever reach the presidency anymore. The difference here is the audience of these word wars. Not very many people could intelligently argue the moral issues involve with Bush’s foreign policy, but a great deal of people (many uneducated ones) could probably give an opinion on Edwards.
Ad-hominem, I think, becomes effective when the audience doesn’t recognize it, or when they recognize it, but agree with it.