I'm honestly more interested in the lifespan of a system, not its ability to surivive a day on Neptune.

While "durability" is key, its rarely a factor in a console's "longevity" making for an innapropriate use of "reliable" as the operative word. But semantics aside, I want a console that will last me 20+ years if not longer, not so much something that can stop a bullet mid flight and still work.

 If you're worrying about Wiimotes in terms of durability, I can confidently say they're more than fine.  I brought my Wii in to school to use Bowling in a review game for exams.  One time, I was quickly trying to reset the pins (i.e. knock the rest down), and I loosely grabbed the Wiimote and began to bowl.  However, as I said, I grabbed it loosely, and it flew out of my hands (no strap) while I was swinging, flew fifteen feet into the air, crashed into the hardwood ceiling, fell down, clanged into the TV, and finally fell to the floor.  When I recovered it, I couldn't find a single scratch or dent.  It's insanely durable.  You should be more worried about what it hits than the Wiimote itself as it's a pretty destructive projectile.