It speaks to Ole Kirk Christiansen's impossible standards: "Even the best is not good enough" (Det Bedste Er Ikke For Godt.) (usually translated "Only the best is good enough.")

Much more strenuous in Danish than the usual quoted translation! but I know some Danish, and most of all that's how Kjeld Kirk Christiansen explained it to an American audience at Brickfest 2003 (IIRC the year).

As I commented elsewhere, it's not 60 years. Sure, the outer dimensions have not changed and are very strict metric Lego Units. [1] But there have been continual improvement that render old and new less than wonderful to use together. You don't really want to mix 70s-early 80s bricks.

Conversely, if you're reselling those old sets, you need to find vintage pieces (though also Lego would use up older pieces and begin to use newer ones in that set)

But bricks from the mature design of the 80s even didn't age so well (clutch too hard, walls can warp), and there have been many improvements to the interior of a brick. All for sound engineering reasons. Thinner walls and internal voids to prevent warp, subtle changes to fine-tune clutch power.

It's a story of continual improvement, but it makes the old bricks seem less wonderful.

Weird thing Lego started to advertise in the 2000s: Lego bricks reach the proper clutch power after 7 insertions! I guess you have to stress-work the new plastic...

[1] I've used a micrometer on pieces of various age and can't get a difference from the outside. Doesn't help that they compress under measuring.