I used small CPU cores if pretty much all my FPGA projects. For example, if I need an I2C controller for a one-time configuration of some external device, inst

I used small CPU cores if pretty much all my FPGA projects. For example, if I need an I2C controller for a one-time configuration of some external device, instead of adding a a hardware controller, I just bit-bang an I2C protocol on the IO pins. Once, that configuration is done, the CPU is then used for some other small task. The use of small embedded CPUs in FPGAs (or in ASICs too) is very common. The capacity of FPGAs is always increasing, and iterating a bug fix in hardware can take hours or even days. With a soft core CPU, updating the embedded firmware can take minutes. For ASICs, you'd need a silicon spin, of course.