In a 2D CAD environment, it’s difficult to efficiently build larger assemblies, and to ensure that individual parts don’t interfere with each other. It also makes it very difficult for a non-engineer to understand what they’re looking at. Think of a customer trying to understand whether your proposed design is actually what they asked for.
Using 3D CAD allows you to create a complete product design that can be interacted with dynamically. This gives you the ability and tools to verify fit and function, and quickly and easily create all the 2D documentation (engineering/manufacturing drawings) directly from the 3D models – making your life simpler!
But it gets better –
Your 2D drawings are synced with the 3D designs, so as it develops, the 2D drawings will update without any extra effort. Furthermore, these 3D CAD models can be used directly in simulation (CAE) or manufacturing (CAM), driving further productivity and eliminating hand-off errors. The auto-update capability extends to all downstream deliverables.
It doesn’t get much better than that, does it?