To me, an internal out of bounds, which signifies poor architecture, is when a ball is in bounds when playing one hole and out of bounds when playing another. The o/b driving range to the left on the 10th at Gulph Mills (a great Ross course) is not an architectural flaw.
When smaller events are held on Bethpage Black, they make the 1st fairway on the green course out of bounds. It's not OB for regular play and they have hospitality there when one of the big ones comes to town, so it's moot. Would you consider that internal OB? Different course, but the same club.
The only real example of internal OB that I've seen recently is at Seawane on Long Island. The third and fourth holes are separated by an inlet. It's about 20 yards across. I don't know if this is how it's always played, but when we play there, the inlet itself is a red penalty area, but if you go over the far side of it that's treated as out of bounds. I think that's reasonable - it's a really pretty bad shot to go over there and no one would try to.
When I don't like internal OB is when it's used to stop people cutting corners. That seems like laziness on the part of the design.
Side note - at the US Amateur at Oakmont, I think the issue in at least some of those cases was the front part of the fairway on hole X, which never gets seen by the elite players is wider than the landing zone on hole Y. That means for an elite player, you have a much larger target going over to hole X even though it's further away from the green on hole Y. Seems to me like, with some prep time, you don't need to make it OB - just make it rough or at least narrower so it's not a preferable target. It'll suck for regular people playing it, but would fix the danger issues for the pros. I don't know how long it would take to make it rough or make it back to fairway again afterwards, so I'm not sure how disruptive it would be.