The "Security by obscurity" claim has been shot down so many times I am not even going to bother doing it again... suffice it to say that the UNIX underpinnings of Mac OSX are considered "Industrial Strength" security.
#2, the purpose originally for windows was to be almost automatic with windows and the internet for updates, and when it was made so, hackers were able to make access to it.
To a certain extent I agree with this.. Windows problems arise from trusting too much... however, Macs also are updated from the internet and are set to check for updates automatically, but the difference is that on the Mac, before you can update or install software, you MUST enter your administrator password. Nothing can touch the core OS files without a proper password... and even that password does not get you access to anything that requires ROOT access.
Of course if you click YES when you shouldn't, you can still invite adware or malware in under the best of situations.
That's true on PCs... Macs still require that pesky password before anything gets installed. Just clicking "Yes" in email or on the internat won't do that much damage. Even then, it could only trash that particular user's files and could not touch anything else.
Macs aren't where the action is for hackers, the number of macs around this nation hardly approaches 10% and around the world the number probably falls like a rock from the USA numbers.
Most of these hacks, viruses, seem to come from Germany, Philippines, which have hardly ever heard of a Mac.
Not having access to such a machine, they know nothing about hacking it and being such a small number, hacking with viruses and such isn't going to be a satisfying for a Mac.
I believe "Security by scarcity around the world" is a legit issue.
On my #2, I think we will see MS improve the security and not have so much trust in the net.
Macs may have the "pesky" security code built in to load stuff, I'm sure you can increase security setting and block lots more access as well.
To be honest, I operate with only a Zone Alarm firewall and don't get infected.
You have to either approve loading or frequent lots of porn site to get infected IMO.