On our small monohull we have the centreboard, when down, angled aft about 15 degrees whereas the rudder blade is angled slightly forward to partially balance the steering. We do sometimes get weed caught on the rudder but not I think on the centreboard, although it is hard to be certain of that since we cannot see it under the boat. That may answer your question!
I have read that angling a keel/rudder forwards does avoid air entrainment, an advantage, perhaps even a necessity, for a Moth, but not relevant to keels that protrude through the bottom of an immersed hull.
I assume that the trend to move the mast further aft is motivated by a desire to set larger screechers, and maybe to some extent by styling. I have heard it said that it reduces the tendancy to pitchpole but I dont think that is true, the longitudinal position of the rig on the hull makes no difference to the pitchpoling moment caused by the foreward thrust component of the rig, at least not until the stern is high in the air by which time it is too late to worrry about it.
Ian Farrier does place the rig and daggerboard a bit further forward than most other designers but his more performance oriented boats can still set pretty big screechers just by having a long bowsprit.