Sean:
I'm on film now talking about just that feature while walking The Old Course ... but you won't be able to see it for another 12 months or so.
To me, at least, the blindness is a less-than-ideal feature of those bunkers on The Old Course. It would be much more ideal (for strategic purposes) if you could see them all, but it wasn't practical there. (The fact that you cannot see them from the tee allows them to be very small without looking silly and out of scale in the landscape, also.) So local knowledge has to suffice. And I am certainly not against a course which rewards local knowledge, by any means.
I love The Old Course; I think I can safely say that I love it as much or more than any other living architect I know. I love that it's closed on Sundays and kids play football on the 14th fairway and dogs try to hurdle the smaller bunkers; and I love that it can be played backwards, which is where a lot of those blind bunkers actually originated. I love that they didn't build the tees up, and I'm not saying they should so you could see more of the bunkers, as (you are correct) most modern courses would do.
But do you really think the anxiety off the tee at The Old Course because people don't know it is a GOOD thing? To me it robs them of all the strategic interest of the course, and gives that all over to the caddie. Anxiety just makes them make bad swings, whereas most of the good players listen to their caddy, pick a line and fire away. I know when I caddied there, it took me a while to learn that I just shouldn't tell people about the Sutherland on #15 or the bunkers in #12, because it just made them anxious ... so I gave them a line and let them hit freely, and trusted not many of them would find those bunkers.
If I had my own piece of flat, sandy dunesland, you'd probably get to see something more like St. Andrews than anyone else has built. But I still rely on clients to pay me to design courses, and I've never had a client who would go for blind fairway bunkers en masse ... not Mike Keiser, not Julian Robertson, not Rupert O'Neal, none of them. And I have not played a new course in many years that had a blind fairway bunker that struck me as a cool feature. Maybe, someday, I'll find the right spot to build a bunch of them; but it's pretty far down my list of ideas to try somewhere.