I am aware that chopper drivers for stepper motors need to be supplied with a voltage much higher than the motor's steady state voltage. For instance most 3D printers use drivers based on chips such as the A4988, which is commonly supplied with 12 V, while the motors are rated for only a few volts. See example motor and driver; the common RepRap 3D printers mostly run on 12 V.
My question is as follows: Why stop at 12 V?
As of my understanding, a higher voltage allows for a faster current rise, and hence better torque at higher speeds. So why not increasing the supply voltage to 18 V, or 24 V, which is still within the specs of the driver?
I can only guess at the possible drawbacks. Efficiency of the driver? Safety? Cost of the peripheral electronics (e.g. caps)? Noise?
Note that my question is not limited to the above mentioned hardware; I am interested in the general limits to driving stepper motors with higher voltages of, say, 24 V.