your preching to the converted mate i agree,a plasterer should be able to cover all aspects but theses wanky courses are here to stay im afraid.
over the years tho its getting less and less demand for it, i use to do a lot for national trust but theyve cut there budgets right back.its the moulds etc that take time.ive an old school spread who works for me and hes a wizz at it,he says back in the day they destroyed every shoe and mould once they run a cornice,so no mould in any house was exactly the same, like an artist to be fair, its a real craft.dont even know if they teach it as part of your time any more,i did it as part of my advanced craft when i was an apprentice.