When I first learnt how to use a Mac it was when OS9 was current, I've worked with them since quite shortly after that. OS10.0... At that point I considered them the best thing for my job (graphics) but didn't want one at home. They just weren't quite there, and weren't worth the extra money for me.
Then I got out of Mac work, and when I went to go back into it I bought a Mac Mini with Tiger on it to swot up and get used to them again. I fell completely in love and haven't looked back.
So since Tiger, yes I absolutely do think they're worth the extra money, desktops AND laptops.
For me the OS is the main draw, but come on, look at them. You ARE paying for style. If you can't deal with that, then they're not for you, but anyone who denies that you pay money just for the design of the thing is a liar, or a little dim. The iMacs are machined out of one slab of aluminium, there's one visible screw on the whole machine. That sort of stuff costs money, and yes some of your purchase price goes there. I'm fine with that, but some people aren't and that's fine. They're a luxury product.
I've worked not only using macs, but more recently selling macs and teaching people how to use them - so I run into all the problems, I'm more than aware of them. I'm not a blinkered fanboy.
If you're convinced you have a 'limited' set of addons, then you're looking in the wrong places. Macs have some of the best third party software houses producing software for them, much of it beautifully integrated with OSX in a way that a lot of Windows programs just can't compete with. The only things I've had to admit defeat on tend to be very, very specific programs with a small market. It's completely understandable that those apps aren't available to such a 'small' player, market-share wise. But then if you need them, run a VM. Piece of cake. There are either Mac versions or Mac equivalents of very nearly every windows app you'd care to mention.
Expecting a Mac to do all your Unixy stuff is expecting too much. If you want to run Unix, run Unix! It's not what Macs are about.
The iLife suite is obscenely good for bundled software. A lot of people assume it won't be, but seriously, dig a little deeper. It's incredibly good, for people who are scared of computers and people who aren't. It strikes a balance that's very hard to get right and does a great job of it.
You don't need to wipe a Mac's arse for it. You can forget about antivirus, defragging, reformatting, all of that stuff. That alone's worth the price bump if you ask me, I hate that stuff. Largely the 'it just works' cliché is actually true. Largely, mind. I didn't say they were perfect. But you can be sure that your Mac will be fast when you get it and stay that fast almost indefinitely. All the average person has to do to a Windows machine to break it, is use it. That's not right.
Some of your purchase price also goes towards the aftercare, which is pretty exceptional - more so if you're near an Apple Store. They'll sort you out. There's not many shops where you can go and pick someone's brain about some problem you've got for an hour and they'll go out of their way to help you, even if it means starting at the beginning and finding out wtf you're talking about first. That sort of stuff is worth money. Warranty and aftercare are great.
There's more, but I've rambled enough. I can't remember the last time something wouldn't work on my Mac and it wasn't my fault. In fact I can't remember the last time my Mac actually properly misbehaved. It just doesn't happen. It just sits there looking pretty and does what it's told.
All three of my Macs do, the top spec iMac (admittedly it was horrendously expensive, but I love it and it won't be replaced anytime soon - I think it's been superceded twice now and you wouldn't be able to tell the difference by using it), the Mac Mini under my TV that runs Plex for me, sits ripping DVDs for hours without making a fuss and has currently been on for 54 days - and that was because of an update, and my parents' Macbook 2.0ghz C2D, which was previously mine, that will quite happily run Aperture and edit raw files.