They should fit plastic ones at the factory, at the very least....
Anyone fitting aftermarket (TT type) guards, have you checked with BMW Motorrad or your dealer to see if you have invalidated the factory BMW warranty?
If you fitted rad guards or even rubber fork boot gaiters to the water cooled F650GS/Dakar etc, BMW would not honour any engine warranty claims, because in their opnion..............airflow and therefore engine cooling had been impeded and compromised
Just worth checking before you fit Rad Guards to your 12GS WC, I would check with BMW - because I think they would advise that you didn't