It usually makes more sense to make a coffee machine that does those steps internally. It's easier in the controlled environment internal to a machine. A espresso coffee vending machine seems to be doing some of them already, like grinding the coffee.
All it's lacking is a cup transport system like a conveyor belt to put the cup in from a cup stockpile and to later serve it. You could even automate recovering the cup, cleaning it and restoking it.
Is there strong customer preference for a robot arm serving the cup rather than a conveyor belt ?
I'd guess for the wow effect. Such a system is much harder to calibrate and maintain than a regular automation line. But a lot sexier also. Maybe the perception and experience of getting the cup from a robotic arm is more appealing to customers than getting it from a conveyor belt?
Somehow I imagined the robot going through the classic steps you might see a barista perform: grounding coffee and putting it in the portafilter, tamping, using the steam wand, etc. The things that might make the difference between a handmade coffee and one from a standard coffee machine.