As others have said, I imagine this is a hangover from the days with classic Macs back in the 80s and early 90s, when the hardware and software was very different, and it did have better support for 2D graphics.
3D graphics were more the speciality of the Amiga platform. Amigas had all the same advantages of Macs over Windows then (and more - don't ask a Mac to multitask back then!) But that shows you how silly the argument is really - just because the Amiga was more suited in the 80s, doesn't mean I should be using one now

Software like Lightwave is long available on Windows.
"Macs" today aren't even the same computers, either in terms of hardware or software, so it's just the company and trademark in common. The hardware is now the same as any other PC (so even the early 2000s claims that Photoshop was supposedly better optimised for PPCs is irrelevant). That just leaves the software, and all the high end graphical software is available for Windows too anyway. As Bregma says, it's more probably that the artists who grew up using Macs years ago now continue sticking with the brandname, even though there's nothing in common with the original machines from a technical point of view.
A super-high resolution might be useful for artists. Though bad for most users - you have problems of not having the GPU power to drive such a large resolution, and things like HD video still have to be upscaled. The reason why most hardware has settled on 1920x1080 is that it matches HD video perfectly, and it's fine for most people. "Retina" is really just a marketing buzzword - you can tell that by the way that they advertise it to mainstream users rather than graphics artists, and don't explain what it is, to pretend that it simply means "better" display somehow.
I also find it interesting that Macs all seem to be glossy displays, when matte is recommended for graphical work (no reflections, and IIRC matte gives better colour reproduction, or something like that). Of course, glossy looks "shinier", which is what seems more important these days, sadly.
Im a windows guy but if you want the bes or near to it, hardware wise buy a mac
But you quote the one single stat of resolution, when there are far more important factors.
I'm not sure if Apple offer something with the spec and customisation choices I got with my Clevo... or maybe they do?
As for the other points:
2 - can't see why. On Windows, I get far more market share, and means most people I know can try out something I write. Even if you consider competition (i.e., that smaller platforms might do better, due to less competition), OS X is well supported enough by software that there isn't that much less competition. And it doesn't have Linux's advantage where users might be more interested to try out less-mainstream games. (On my cross-platform game, the Mac version gets the least downloads, after Symbian, Windows, Linux and Android.) For development itself, that's personal opinion - some people like one platform better, others like other platforms.
3 - no evidence of that. The specs that Macs come with make the idea that Windows is bloated rather laughable - again likely a throwback to decades ago when the Mac platform did have lower requirements than Windows.
4 - Probably safer, but more due to being a smaller platform. I see no evidence of greater security compared with Windows Vista or later. And not really an important issue - MS Security Essentials runs in the background, never bothers me, and I've never had virus problems.
Use whatever platform you like. It's a matter of personal preference. I get annoyed by fanatics who constantly try to ram their choice down my throat, or claim that their choice is so much better, or did everything first, without using any evidence or logic in their arguments. And I'm not saying which, but these days one company gets more of those fanatics than any other company or platform...
in contrast to most PC laptops that either feel very plastic, or very clunky or both, even when they are physically small.
Remember that the same can be said of many PC companies with high end hardware. When we're talking about hardware, we shouldn't polarise it as "Mac vs PC", as Macs are just another make of PC. I could say how in my opinion, Clevo offers wonderful quality, better than most PCs, or so does Samsung (e.g., my Samsung netbook has a much better keyboard that the poor quality ones I've seen on any of the Apple ultraportables, and other makes).
Indeed, this is the fallacy I hear most often with Apple PC users. If someone bought a good expensive PC from any other company, they'd just say it's a good PC. But if it's Apple, then it then gets compared against the worst excesses of the poorest other PCs, and then this gets generalised into "Macs are better than PCs!" Saying that one make of PC is better than average isn't really that strong a claim when you think about it - and a very different claim to saying that Apple are a better PC manufacturer that *all other* PC manufacturers.
(I'm not saying that you're doing this - but it's something I often see done.)