The problem here is you changed customers and didn't realize it. In the beginning your customer was the end user as you helped them implement. When you went to development your customer was no longer the end user but the business unit. It is their job to determine what the end user needs. Your job is to ensure business gets what they want. Take pride in doing a good job for them.

You may want to consider product design or starting your own project so you can do the product design, though. It sounds more like what you want if that is where you find your joy.