It is one reason why I encourage my s/w dev colleagues to go and spend time in customer support. The environment of what your users experience can be fundamentally different to what you imagined during the development phase.

My eyes were opened when I worked on one product. We added scriptability and for 3 years we assumed that would cover a multitude of user requirements. Until I actually tried to implement a customer's solution using it and realised how crap the experience was. 3 years late.