Lol. It never bothered me, especially since it's used a lot in the play. I thought you meant that a metal bar came down and blocked the view, I didn't realize you were just talking about the whole set. That's like saying the proscenium in Hello, Dolly! was distracting. Yeah, it's there the whole time because if it wasn't, it would just be a blank stage for much or the play.
I wasn't worried about the actors' safety but I did have WTF moments at MFL with the bar that they exited from a cloth panel on the side and Mrs. Higgins "house" which wobbled as it settled into place when people opened and closed the door. I can't remember if the bar wobbled as well.
I saw this godawful show off-Broadway. I think it had something to do with Peter Pan and it was way too long. Anyway, there was a lot of scaffolding and such and the actors climbed all over the set. I definitely thought it seemed unsafe with the way they were clambering over it. At best, I thought someone might hit their head or get a foot caught in something.
In high school I definitely worried that we were going to die whenever there was a scene where the whole ensemble got on top of one of our building set pieces. Structural integrity is not the phrase that comes to mind when I think of those sets. It's probably good we only ever did a handful of performances.
If we're just talking ugly, I continue to be surprised at what the Met Opera will pay for. I guess they wanted a storybook feel for Die Entfuhrung aus dem Serail but that set looked cheap af. Especially the trees. There are worse sets but I think I've blocked them out.