Voltage Requirement for Integrated Circuits
The technology trend on ICs are to have them become smaller, faster, cost effective and low power consuming. Shrinking of transistor size is the major drive in this industry but shrinking the size leads to smaller voltage tolerance of breakdown that's is one of the reason why the supply voltage reduces the other being low power consumption of course.

Having said that certain application needs certain ICs with certain requirements for example power ICs are needed to handle high voltage, no escaping that. Or Analog circuits such as amplifier if one requires a high gain then one has to go for an amp with probably higher gain (with higher supply voltage) and so on...