Borg

All they really needed to do was take D2 and update it. Reinvention was not required. The skill system, the stat points, the classes, the game play, the feel of the game etc. It was all perfect. The only thing that really needed modifying were the graphics and additions to the quests and item system. D2s issues were items and how item based classes generally are. All that needed is some decent fixed quest items, to ensure all classes can fight effectively and then a new crafting system.