OP here,

We prefer to use PIC microcontrollers because they come in a DIP package.

Our products are mainly sold as PCBs that a customer assembles in their own home, appealing to the DIY electronics market.

For many, SMD is challenging, so having a DIP package makes us more available.

Additionally, the ability to use less power is useful because our products do not have an onboard power supply, instead relying on the rack's supply that may be shared between many products.