Whether trad or WFP the sills have always been cleaned, so far as I'm concerned that is the minimum that should be done.
Frames when trad were extra, though if they were already very clean, I'd often give a quick wipe around with a damp scrim just to keep them looking tidy.
Now I'm WFP the whole lot gets done, doors and frames included, and especially all the UPVC right up to and including the guttering on conservatories.
I've found it to be a huge selling point in truth, and it is still way quicker than doing them trad and only doing the glass and sills.
Ian