VR Toolkits: Why do we keep reinventing the wheel?

CalVR, MinVR, ViSTA, Virtools/3DVIA, WorldViz, VRJuggler, TechViz, FreeVR, VRG3D, MiddleVR, CaveLib, EONReality, VRUI, WorldToolKit, ... This is a short (very short and incomplete) list of some of the toolkits and software out there that users can choose from to develop their interactive VR applications. Some are commercial, some are free, some leverage other software and they just take care of the display/interaction part, some allow full-blown control of all aspects of the graphics pipeline, some provide simple visual interfaces, some require extensive programming. How do users choose? What makes universities and commercial companies decide to start from scratch (again) and create their own toolkit? What´s wrong with all of these? What´s right with all of these? In this panel we hope to bring together different perspectives from academic developers, industry developers, and users of VR toolkits, to try and understand what makes a VR tool successful and why we keep thinking that all of the developed tools out there are never quite right for our needs.