This is not a CPU, but a MCU, targetting external circuitry, so yes, IO speed is very important.
You might want to interface some external device that can't be driven with any existing hardware peripheral, and as you may know, 8MHz isn't lighting fast, most basic PICs can toggle it faster while running a lot slower, so depending on the application, you might waste a lot of cycles.
I just found strange that it took 15 CPU cycles to toggle a bit, directly accessing the register, and 30 when running dual core, wasn't sure if this was a memory bottleneck or what, until I later found the APB bus runs at 80MHZ.