Sean
I think you'd agree that you get degrees of forced carry. As I referred to in an earlier post having 50 or 60 yds of gunge in front of the mens tee, whether that gunge be gorse, heather, thick rough or water is not going to be a concern for most golfers and I doubt you would right off the hole as being penal. If the carry was 150 yards plus that would be another matter.
Likewise, the positioning and extent of the forced carry. With reference to the 3rd hole at Carnoustie and indeed the first at TOC, where you have a shortish par 4 with a burn bang in front of the green, then do you say that is penal architecture ? Bearing in mind that generally players would be hitting a short to mid iron approach.
Then there is the burn in front of the 18th green at Carnoustie. That's a more dicey approach and for many, maybe not all, asks a serious question of whether to go for it or lay up. Risk reward or strategic, take your pick, but I don't think that in this day and age with modern equipment etc that a reasonably competent golfer who decided to lay up would consider his next shot as being penal just because he had to cross a relatively narrow body of water that was well short of the intended landing area. Obviously if instead of a burn you had a lake that extended 100 yards back from the green there would be no argument that it was penal design, especially or perhaps if there was no room to go round it.
So, I don't think it's entirely black or white in terms of cross hazards making a hole penal.
Niall