Agreed. Mac malware is becoming increasingly common. Even windows malware which will use a Mac as a benign host to get inside someone's home network! The perception that Mac's are immune to attack has been around for over 5 years now - and that perception itself has made users complacent and more vulnerable.Viruses are less prevalent in Macs. Not immune by any stretch of the imagination.
As for running without AV/Anti-malware tools, it can be completely safe to do this. I have never had an AV alert on one of my windows machine and it's fine. Furthermore, even operating system patches are not essential to avoid infection. The same windows machine I referred to above is running XP SP2 (since SP3 didn't like my hardware) and hasn't had updates in several years without issue. I don't have flash or java plugins in my browser and use no-script (firefox extension) extensively.