Using a PIC microcontroller
There's never a case where you have to have a microcontroller, at least not technically. Anything a microcontroller does can also be done by an appropriate combination of discrete components. What the microcontroller buys you is size and flexibility. The microcontroller does the job in a smaller package than the discrete components (which sometimes makes the difference between practical and not), and can be programmed to do a different job vastly more easily than a discrete component circuit can be redesigned.

There's also the fact that many engineers, especially younger ones, know microcontrollers far better than we know discrete components. I wouldn't know what to do with a 555 timer or a hex decoder or half the parts on the more dusty shelves around here. But I know I can accomplish all those tasks in a smaller chip. So if you asked me to design something like that, it would have a microcontroller just because that's what I know.