I'm not saying they would want a marked course.
I think Tim does make a good point. I can see the appeal of marked courses and in reality if you go to most races locally to me they are more or less marked in some way all the way, whether that's because of the presence of lots of marshalls, keeping to established tracks and trods.
It's the longer ones where the navigation comes in and it's not that feasible to mark them anyway, unless they have a PPP style budget.