I think Ross wrote that par 3 holes could be a little more difficult. I also think they can, because you can control the distance of the shot with multiple tees so the yardage is appropriate to the various levels of players skill set.
I would say MacDonald thought they were good for "concept shots" like the Redan, Biarritz, etc., although the short is certainly all or nothing. I tend to agree, since half the strategy of a shot should be tied to the previous shot, which isn't the case on a par 3.
For some unknown reason, I recall watching TV golf as a kid interested in architecture and whoever the announcer was back then often referred to par 3 holes as "straightforward." Generally, it was describing a green mostly surrounded by bunkers as you suggest. So, maybe for a time in architecture, the idea was that a par 3 should just be an accuracy test? Don't recall the exact holes that I recall, but if you figure they were playing Wilson or RTJ courses back then, maybe they were? Does anyone recall a strategic par 3 from those guys?
As to bail out shots, yes, its strategy, but I always think of "what part of the green" and "what is the best shot pattern?" a better strategic question than "do I or don't I?" I guess bailing out to the wide, unguarded edge of the green is a classic strategic question, vs. going closer to the pin, but not baling out short and wide of the green. However, there was a tread about greens falling away from the bail out that hits a few good points.