Jamie,
I agree that it is the way to achieve that.
A sand bunker penalises a poor golfer far more than a good one, whereas a grass bunker can exact a strong penalty from the better player while allowing a lesser player to advance his ball a considerable distance up the fairway, or get onto a green he has missed hitting in regulation.
The centreline fairway grunker on 16 at Huntercombe is a great example. A hazard like that in the driving zone stops a better player from going for the green, or at least for the pin, while the lesser golfer whose goal is to just hit the green somewhere, or even get near the green, is more able to do that than if he were in sand.
Furthermore, I think grass bunkers can be deeper and bolder than a sand bunker (especially as a driving hazard) as a result of that greater playability for the lesser player.
At the green, the better player who expects to turn a missed GIR into a par a good percentage of the time will have a harder time doing that from the rough of a grass bunker than from the sand, while a lesser player whose goal might be to just get it on the green and two putt most of the time will have an easier time doing so from grass than from sand.