This was sort of explained in the first movie by Agent Smith. He explained that the first Matrix was designed as a utopia, but that the humans connected to it rejected the program, and "entire crops [of human Duracells] were lost". He goes on to say that the Matrix was redesigned into its current form, "the peak of your civilization". So it was done to ensure that the people plugged into the Matrix would not "reject" it.
Of course, the real explanation is that if they did design the Matrix as you suggest, there would be no movie.
