I can feel how frustrated you are. I can tell you what I think happened, and how we insure that doesn't happen in our cosmetic dental practice, but can't say for sure what actually did happen in your case.
First, your dentist made your temporary veneers with a plastic material. Your permanent veneers were made by a dental technician with porcelain. One reason why did weren't the same as the temporaries you liked, is that your dentist did not communicate very effectively to the dental technician (ceramist), or the ceramist did not read the instructions. However, there is a way that this can be prevented, and this is how we do it in our office.
First, we discuss smile design with the patient before anything is ever done. What they like, don't like, want to change, and how they want it changed. Also, how long the front teeth are and any changes needed to make the veneers longer or shorter than the original teeth. Color, what color does the patient want the veneers to be? The same as the natural teeth, or whiter or darker? How many veneers does the patient want? Many questions, and until all these questions are asked and answers determined, neither the dentist or ceramist can design the final veneers.
It sounds like your dentist made your temporaries the way you wanted your new smile to look. Then all he had to do was take photos of you in your temporaries (we call the temporaries the "trial smile"), measure the lengths of the teeth, take an impression of the temporaries for a model of the temporaries to be used by the ceramist as his template. Then your dentist also needs to accurately tell the ceramist the actual color to make the new veneers, along with the color of the underlying teeth after they were prepared. And, if he's really a good cosmetic dentist, he will discuss the surface texture and incisal translucency and if or how much of each you would want. If your dentist did all of these things and gave the ceramist accurate instructions on how to make your veneers, there is little excuse for a huge disparity between the temporaries you liked and the actual veneers that were made.