"their" hardware?
are you talking about the INTEL cpu?
or the SAMSUNG ram?
or the LG panel?
or the AMD gpu?
or the BROADCOM bluetooth/wifi?
Would you believe this collection of parts from various vendors can also be assembled by someone other than apple, and can run OSX even better than the collection of parts assembled by apple. For example the imac is "slim and sexy" that's great. The restricted airflow causes the cpu to throttle itself if you attempt any continuously demanding task, never allowing you to fully utilize all the ghz you paid apple for. Alternatively if you build one with the same parts, and give it adequate cooling, not only will it last longer, but you can also utilize all of the ghz you paid for. Talk about a win-win.
Apple make a particular class of device, if you think the Macbook or MBA is thermally constrained, seriously go put a Surface Pro 3 or 4 (i've had both as work machines) under load and see how hot they get. I've run an SP3 for 12 months as a work machine and just upgraded it to an SP4 (windows devices at work).
ALL mobile machines in that sort of form factor throttle. They are not intended to run at max speed for sustained periods, they're intended to clock up as fast as possible and "race to sleep" to conserve battery life.
And yes you can buy/build the same/similar internal components cheaper. You don't get OS X, you don't get the apple level of customer service and you don't get anywhere near the same quality trackpad or materials in terms of the case.
2-3 year old PC laptops look old. They go shiny where the texture wears off the plastics, the key go shiny/wear off, etc. Macs generally do not.
You get what you pay for. If you're lucky.
A computer is more than the sum of its internal components. It's no secret that apple are an integrator, rather than a component manufacturer for the most part. Things like the screen, keyboard and trackpad are the difference between a machine that is annoying to use (e.g., most DELL, HP or ASUS portables i've ever used) and something that's actually pleasant (e.g., an Apple machine with an apple trackpad).
