Bart
Very good questions. To add to Jeff and Neil's comments regarding camouflage, and I hope without repeating them too much, Mackenzie's criticism of blindness is his argument FOR the application of camo principles. He wanted the golfer to see everything...so he could manipulate the golfer as he liked.
Mackenzie wanted as much as possible to be visible - but not for everything to be as it appeared. Two examples of this are his desires to make holes or shots "look hard but play easy" as well as to give the player thrills. He was thinking beyond the physical challenges of playing the hole to the mental and emotional aspects.
So, Mac's use of camouflage in golf design wasn't about hiding things, in fact (and understandably something most get exactly opposite) but about making things visible -- then manipulating, controlling, the way the golfer experienced the hole. As a camouflage expert, Mackenzie knew he needed our eyes.
Fundamentally, camouflage, no matter where or how it is applied, demands a shift in how the camoufleur thinks and creates. He has to see his work not in terms of the work as it is or even as it appears to him, but how it will be processed by the "user's" brain, ie the totality of the experience. The camoufleur must shift his focus from the object or figure (golf course) to the subject or signal processor (golfer). As Neil writes, blindness removed the "input signals," and with nothing to process the camoufleur's talents would not be needed.
Mackenzie didn't want to remove input signals, he wanted to control them. He often gives us too many signals, in fact, like a green from another hole that we might think is the green on the hole we are playing, or a green that appears smaller than it is because of huge bunkering (sensory overload there!) surrounding it, or a green that appears closer than it is due to the use of swales and / or bunkering. Playing a Mackenzie course can be a uniquely cerebral experience - with an interesting mix of emotions thrown in, too. He is toying with us, challenging our knowledge of ourselves and our games, and using fundamental notions involved with camouflage as a military doctrine (rather than camouflage as a set of tools or bag of tricks) that range pretty far afield of anything a designer would come across in studying course design.
I know this might sound like academic gobbledygook, but as you read his writing, take note of how he writes about a feature, a hole, an element, whatever. He writes often about a lot more than the simple facts of the thing: he writes about the experience, the way the golfer will interpret it or feel about it. The story he tells about the Scot who calls the water hazard a "bonnie burn" when he clears it and a "doomed sewer" when he fails is one example.
So in a way I think your questions about blindness miss the mark a little. The fascinating bit then about a Mackenzie design might be that at first glance "it's all right in front of you"...when it's really not.
Another point: today we think of blindness as a tool or design element available to designers, but back then I think Mac was writing to a generation of designers who accepted it as legitimate or at least as a reasonable compromise to unsolvable routing problems.
Today, we solve that problem with a bulldozer. This makes the question of blindness entirely different. Mac's argument was that blindness was the lazy man's way out.
So to answer your question...
I think there's a difference between blindness when used by a modern designer to play with us, with our emotions -- because unlike then we don't see it too much -- and blindness back then, when it was the product of a compromise, and far more common than today.
But then as now it comes down to: does the blindness give you pleasure, does it enhance your experience of the hole?
Mark