You will find there is a great deal of denial about OS X and it`s security which results in false security for many, as they assume that all have the same usage and workflow, which is generally never the case.
As someone who relies on their Mac`s for a living absolutely yes OS X does require protection above and beyond what Apple offers, I see the same question, same rhetoric, over and over;
There are multiple reasons to run antivirus/malware detection on OS X especially if you are dealing with mixed environments. Passing on malicious code, even inadvertently will do you no favours in the professional world, let alone your family and friends. What does not hurt OS X may well bring a Windows based system to it`s knees. By far the vast majority of companies that you may potentially work with, or interact with will require a level of antivirus protection, regardless of platform.
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Q-6