Implementing new business software (such as ERP software) can be daunting. Most people are averse to big changes in life. Why? Because change is disturbing, and can cause feelings of anxiety and insecurity. Think about any major change in your life - even moving from high school to university or a full-time job can be quite difficult to manage emotionally, at least in the beginning.
One factor that's frequently overlooked is denial. Denial is the classic first reaction in the face of trauma or loss. But the same basic human reaction comes into play when you face major changes in life (and work) - things have changed, and even if they've changed for the better, the initial reaction is often to believe that life will go on exactly as before - and therefore resist accepting that change.
You see this when a batch /paper based ERP system is replaced by a date-sensitive modern system. The old system required printing and filing multiple copies of customer invoices. With the new system, you need only print the customer's copy - any other copy you may need can be retrieved online. Now that's clearly a change for the better, yet many people in this situation either continue printing and filing those multiple copies, or if they're unable to do so, become resistant to and negative about the new system.
As implementors, we need to understand and accommodate this. In this example, it may help the user to continue printing and filing some copies initially, and there's really no harm in accommodating this as long as there is a clear plan of action to re-visit and eliminate it after a certain period of time - namely after the denial stage.
A good business software implementation consultant needs some soft skills to complement business, analytical and technical expertise. In my experience, though, very few actually do - many seem to want to browbeat their clients into accepting the systems and procedures.