Actually it is! The failure rate for a MacBook Pro was way under 2/10 when I was there during the lifespan of the product.
Apple calculates the lifespan of a product in different terms to the warranty. The warranties differ by country (EMEA & US have different warranties thanks to EU and individual state laws).
You're right that these machines can and will go for five years. My current laptop, a 17" MacBook Pro, has been with me since ~2007. It'll go for another year at least.
Apple will replace these devices when they are in warranty. True. But the concept of a warranty is what is wrong, not the replacement of an entire device.
It's better to have a device which is far less likely to suffer mechanical failure, which happens to require a more expensive repair when it does, than it is to have a device far more likely to suffer mechanical failure but with cheaper repairs (for a few select problems).
If you can't afford a MacBook Pro don't buy one. There are other machines on the market which are highly user-replaceable. I'm going to buy the new Retina, I won't be getting AppleCare, and I bet it lasts just as long if not longer as anything else you buy.
So yeah, I can afford a MacBook Pro. I'm just choosing not to, anymore.
But I'm probably not going back to Linux (where I came from). Honestly, Windows doesn't looks so bad anymore. I admit I don't know the first thing about it, but maybe I'll give it a try.
Integration with tools like git and svn are only through 3rd party solutions, and aren't as polished as one would like.
I could get by with it, but I would prefer not to. However, I'm also not particularly happy with the idea of going back to Linux, and my work still requires a Mac. Thus, stuck on Mac OS X.