Mobile Apps Prototyping

Probably every company has faced the following problem - you are starting new Mobile app with really outstanding idea. All tech processes are adjusted and the project is being developed by experienced developers, designers and QA engineers. Seems that everything should be fine, but when the app was uploaded to the App Store the users receive it coldly. "It's so inconvenient, the app's logic is unclear at all!" - they say. Then we try to find out whose fault is it and blame everyone - the Designer has done wrong Interface, the Developer hasn't thought over the logic. But everyone forgets that all team members' work is based on one initial document - the Specification. And usually the root of all problems is hiding here.