The title might seem like a typo or misprint. Aren't we looking for "Built to Last" when we're shopping? How could baked-in transience be a virtue? Is this more of that silly Geek Talk [tm] wherein "laziness" is a virtue? You betcha.
The "new car smell" everyone talks about isn't just or only a smell, but the whole ambience of having a new car, unblemished by actual use, like a puppy on its first day in the garden. Such innocence may be annoying in some contexts. A fresh laptop is maybe so far from customized to what one needs, but let's not turn pessimistic.
In the Cloud, the analogy is obvious: "build one to throw it away" means we're free to "just doodle" with some serious resources at our command. Spin up some JuJu on Ubuntu and define yourself a rig, a rack, a framework, or whatever. Test your business model, fine tune, unit test, keep it agile. You may want to take it live, but probably after a number of iterations. Alpha versions mature into betas until an actual release candidate is rolled out to the world.
Likewise on the first day of school, one's desk is pristine. Students used to have desks unto themselves, not just lockers, where possessions were conveniently stored, persisting from day to day.
That practice may have eroded in many districts, or never caught on. My personal memories hearken back to the Overseas School of Rome, one classroom in particular. They tilted up, those desk lids. Lockers start pristine also, at least if all the old stickers come off.
We know from the get go that experiences are a lot like novels or films: they start, have a middle part, and then they're over. Life is episodic. So the specification that it "not last" could be said to belong to "experience itself" (getting philosophical here).
When you know going in that it's a doodle or throwaway version, might you take more risks? Would you enjoy it more, and therefore gain more, from the challenge? When the changes are more permanent, one likes to know in advance about one's choices, and mull them over.
However, like ice cream on a summer's day, accept in advance that even with the privilege of choices, none of them were "built to last". Some elementary particles only fleetingly exist before separating into decay particles that in turn interact and so on. Lightning happens in a flash.
Role-playing games involve rotation quite a bit, or can. You're not stuck in a role forever and indeed are better at role playing more generally for having moved around and seen the game from different points of view.
The idea that you needed to be just that one thing when you grew up, like "the milkman" or "the nurse", was a tad too simplistic to ever gain much traction. Life goes in chapters. People were not built to be typecast necessarily.