But we do. The "re-inventions" just tends to be increasingly subtle, because the high level structure continues to make sense and the overall designs are simple to begin with, which makes it hard to come up with revolutionary new ideas in the space.
Umbrella's for example see continuous evolution in means of making better fully collapsible versions, making the deployment more automated, reducing weight, etc.
From Wikipedia, illustrating both that there's continued substantial effort in coming up with new ideas, and at the same time that it is hard to come up with something genuinely new:
> Umbrellas continue to be actively developed. In the US, so many umbrella-related patents are being filed that the U.S. Patent Office employs four full-time examiners to assess them. As of 2008, the office registered 3000 active patents on umbrella-related inventions. Nonetheless, Totes, the largest American umbrella producer, has stopped accepting unsolicited proposals. Its director of umbrella development was reported as saying that while umbrellas are so ordinary that everyone thinks about them, "it's difficult to come up with an umbrella idea that hasn’t already been done."[36]
They are significantly more, but it's not just replacement cost avoidance that's the benefit. They are easier to handle in wind, keeping you dryer and not having to fight the umbrella.
People come up with ideas for frustrating things they have a lot of contact with; seemingly every HGV driver has "invented" a way to automate matching cab (ie tractor) plates to trailer plates.
People buy cheap umbrellas, they suck, the people imagine better umbrellas that cost more: goto START.
A 9yo of my acquaintance is really inventive; he often says "what if we had something that would ...", yes, if you'd invented and developed that 50 years ago you'd have been a multi-millionaire.
A lot of inventions arise naturally out of a creative mind being confronted with the problem.
Umbrella's for example see continuous evolution in means of making better fully collapsible versions, making the deployment more automated, reducing weight, etc.
From Wikipedia, illustrating both that there's continued substantial effort in coming up with new ideas, and at the same time that it is hard to come up with something genuinely new:
> Umbrellas continue to be actively developed. In the US, so many umbrella-related patents are being filed that the U.S. Patent Office employs four full-time examiners to assess them. As of 2008, the office registered 3000 active patents on umbrella-related inventions. Nonetheless, Totes, the largest American umbrella producer, has stopped accepting unsolicited proposals. Its director of umbrella development was reported as saying that while umbrellas are so ordinary that everyone thinks about them, "it's difficult to come up with an umbrella idea that hasn’t already been done."[36]
(https://en.wikipedia.org/wiki/Umbrella)