...b) Arms and linkages don't have to have super tight tolerances, because accuracy is achieved by tightly integrated visual feedback that's easy to program and low complexity processing.
Ability to program easily with a GUI and visual interface that sees things from the robots' camera perspective.
Flexible use of coordinate spaces that make programming arms with 6 or more degrees of freedom super easy. Got a bot arm with 13 linkages that can reach around corners? Easy. Simple arm with only 2 degrees of freedom, with one polar and one cartesian? Any arm geometry works.