Task Manager in Microsoft Outlook is probably to blame. It set the standard low enough for the task management systems that followed it.
Task management software, workflow tools and to do lists have been an active area of development for entrepreneurial startups over the past few years. A big stumbling block for their adoption is that they can be too generic for the specialised needs and terminology within law firms.
BigHand has come to the rescue!
BigHand has created BigHand Workflow Management. It is a task and workflow tool for interactions between lawyers and support staff and also amongst support staff who handle only back office functions.