One example close to home for a lot of us is at Architects--the first hole, meant to approximate Old Tom Morris.
The wall is fully contrived, but it serves as a boundary for the left side of the hole, and really isn't in play, for all levels of player.
In this case, I understand what Kay and Whitten were doing here, which was giving the look of British courses that featured real walls. The were wise enough, however, to move it well off the lines of play, so it's simply a visual and not part of the strategy of the hole.
I don't dislike it, but it's not something that makes me itch to play the course either--it's just there. The whole course is contrived anyway, so it's not that big of a deal, in my mind.
In the case of Whiskey Creek, I simply play around it, and look at it from a distance. This is very much in play for all levels of player, but I like it, simply because I think it adds something to the property, a little bit of strategy (can I hit driver past it down the right, or take fairway metal and be short of it...?). The nice thing is, the golfer isn't penalized for being left of it either, as there is still plenty of room on the left to hit either a layup or an approach. The trees I'm not so sure about, I suppose the architects felt the immediate area just needed a little extra something to fill the space. I don't feel they affect the shot that much, it seems possible to hit a low layup under or a high shot around/through.