I also noticed that in very old pics, the entire alps bunker was fortified all around by sleepers/ vertical wood face. The front is now rivetted- maybe for safety?
As far as the slog dynamic- it was probably more exciting from a match play perspective. Each hole gave you a greater chance to separate yourself from your opponent and each mistake wasn't necessarily as costly since you'd have a chance to catch up. And how draining could a round be that only takes 2 hours to play?
One other thing that I keep coming across with Prestwick reading is that the conditions of the fairways and greens were about the best on Earth. I would think that it wasn't much different in that Marr/ Jacklin video than in the 1800s.
Next time I go to Prestwick, I'll try playing it with a gutty and pre 1900 clubs from the forward tees and will report back.