Endeavour's Final Journey
As I was watching the Space Shuttle Endeavour fly overhead in the Bay Area on its final voyage to LA a couple of weeks ago, I was quickly reminded of one of the more interesting stories in technical evolution.
The size of the Solid Rocket Boosters (not pictured) were determined based on the size of the railroad tracks used to transport them from the factory to the launch site, which has to go through tunnels. The tunnel size, of course, was based on the size of the rail. The rail's size was determined over generations of use, dating back to roman roads and the chariots, which were defined by the two horses which pulled it. Essentially the design of the most advanced technology we have today was determined by the size of two horses' ass.
I was first introduced to this story in Kevin Kelly's book "What Technology Wants" and again in a more abridged explanation at Astrodigital.
The lessons of inter-dependencies between design decisions over time here are enormous. While it's impossible to know every possible future use case for your product, taking a moment to consider what path you're paving which others will have to travel (including yourself) may be worthwhile.