I think that the advantage is that AppleCare covers most of the Apple peripherals that you use with your Mac, therefore if you indeed run into problems during the coverage you can get it replaced.
By the way, cool avatar! Dark Castle was my very first game on my first Mac--the old venerable Mac SE with a whopping 20MB HD.
Maybe I've been lucky, but in 20 years of using PCs and Macs, I've never had one fail after the warranty period, or an extended warranty provided free of charge on my credit card.
Of course, I've changed HDs, upgraded optical drives, and changed power supplies. All very simple, and hardly worth buying insurance for, since it's more efficient to do it myself. Not to mention, most of us even remotely tech savvy can do a better job on simple part replacements than the Geniuses.
Regarding peripherals, I tend to buy the most cost effective part. For instance, I'll opt for an OEM optical drive, as opposed to buying Apple's. At $26, if it broke, I'll just replace it and won't even bother with the warranty claim process, much like all of my peripherals.