Of course the customer cares about fast, powerful and efficient things they can use.
What happens is that most of the time making something fast, powerful and efficient implies so much resources that the ambitious engineer can not complete the project in time.
Customers prefer something that works today, even with limited functionality that something perfect that only works inside the mind of the engineer.
That is the reason Steve Jobs said no so many times, because this way his company could ship products in time.
That in engineers mindset problem: It is painful to say No, like the song says, we "want it all".
Not only that -- a lot of people pursue "innovative" technologies and try to build something all new, when existing ideas have only reached 1% of the market that need them because it takes a lot of work to actually get people on board.
We like building things, and making them fast and powerful and efficient.
The customer doesn't care about any of that though. They just want something that helps them.