This argument is a bit narrow, I think.
While it's true that Macs hold their value amazingly well, your argument is valid if you are in a constant/periodic upgrade cycle. As an Apple user, this makes sense, and Apple is counting on it as well, which is why they do this. They "lock you in".
That said, a machine that is easily repaired (like the Blade Pro) can be kept running for many, many years fairly easily. Hell, the
base specs on a machine like that
far exceed anything Apple will put out in the next 3-5 years, if ever. The fact that Msoft supports machines basically forever is another factor, plus, there's always Linux. So the reliability factor is somewhat mitigated.
Granted, this is not the machine for the target Apple user: one who is confortable with buying a car with a sealed hood, unlike a lot of people here. Apple is just pushing us technical folks out, is all. Which makes this so frustrating and we come here to vent.
If Apple had built a Blade Pro, I would have
sold my soul to get it so I can finally retire my 2011 17"...it's
that perfect (but
Windows 
).
But alas, now I have to take a chance on it (it's
still at the very top of my list).