In a word, not designing for the target group. (Sorry, that wasn’t a word but an entire sentence.)
For those of you who may not have heard of Juicero, it is a very expensive juice maker that started off as an even more expensive juice maker. Because of numerous reasons, many of them justifiable, it became both a symbol of the mindless excesses and vanity of Silicon Valley as well as the laughing stock of just about everyone. This post, being hardware-oriented, however, is not about either of those, but about the reason why Juicero is so expensive.
In a sentence, it is so because it was a design and development process unfettered by the constraints of budget or for any particular target group. I remember from a long time ago, a company called “Boston Acoustics” used to have an ad for its audio speakers that went: “It is easy to make a great speaker when money is not a constraint. Try make a great speaker for under $400” (or something like that). Constraints are great because they ground us to reality, they make us find solutions to real-world problems, they make us creative. A blank canvas is great, but the canvas has to have edges. An unlimited, edgeless canvas can lead us to just as bad a result as a complete lack of freedom can.
Ask yourself: If you could do anything, what would you do?
Read on for an excellent analysis that has great lessons for us in hardware design, development and, most important, creating for the real world.