Soft cores are often used as a convenient abstraction layer in FPGAs for example. Rather than hand coding control plane in VHDL or Verilog, you can compile regular C and manage your device that way. But C compilers require a target architecture to compile to, so you need to pick one.

A side note. There are many options for soft cores and often you will see overengineered solutions because something is popular or ready off the shelf. You end up with powerful gadgets. Kind of like a toaster toothbrush: Both are useful on their own, but it’s a weird combination.