3D printing is valued in commercial settings for its ability to streamline the design process.
3D printers are really just lower-cost, somewhat less-capable, rapid prototyping machines.
3D printers have some additional, generally-agreed-upon defining characteristics:
They can be used in an office environment.
3D printers are generally small and in some cases can sit on a desktop.
3D printers make smaller parts.
Being smaller on the outside means there's less room to build parts inside.
3D printers are easier to use.
As a consequence, they require much less or even no training at all in contrast to rapid prototyping machines.
3D printers are an example of the popularization and progress of a technology.