SharePoint is a powerful tool for collaboration and information sharing. Working on documents, tracking issues, tasks and projects can all be made easier using the tool. In many demos I have seen SharePoint can be used as a complete solution for managing the complete life-cycle of a business process. It all seems so great.
In the real world of actual organizations (at least in my experience) not everyone is willing or interested in using SharePoint. There are ways to integrate external applications with SharePoint that can create very powerful solutions but in some cases the issues is more than just connecting to other data sources. There are cases where you just need to pull information out of SharePoint for a report to management or for a meeting where you will not have access to your SharePoint site.