Being imprisoned doesn't mean you are weak. How powerful characters aren't some binary thing. Sargeras may be imprisoned now but theres a reason why he is that way, he's dangerous. Same with the Old Gods.I didn't fall through the flowers very often, but when it happened it would happen even in the dead center. Although maybe that was the actual problem. Trying to recall vague memories, I think it happened less often on the edges of the flowers, weirdly enough.
On another note, I was just looking over the encounter journal and I'm a bit worried. I recall it originally being assumed that Arthas wouldn't be in the expansion at all, though the quote was more along the lines of "we're not going to put him in without respecting his story" or something. The encounter journal is implying Arthas might appear... as just some generic raid mechanic that's holding Anduin back. That feels like the exact situation they didn't want to do. It's worse than not including him at all, in my opinion.
It's like some monkey's paw, and it reminds me of Sargeras. There was lots of concern that he was too powerful for us to fight and us beating him in a raid fight would diminish his character. And we didn't beat him in a raid fight... he got defeated incredibly easily in a cutscene without even needing us to contribute.
It also feels like Ner'zhul. Unlike many others, I didn't mind Ner'zhul's role in Warlords of Draenor. The whole point was that it was a timeline in which he didn't choose that path that made him into the powerful Lich King. If anything, I think his fate ended up a little too much like his original self despite completely different timing and circumstances. However, he just keeps appearing in the main timeline in pathetic roles that are really disappointing, especially considering the confirmation that he absolutely was holding a greater evil back when he was the Lich King. I think he should be too far gone to have a significant plot role, but I didn't like beating him up as a generic boss to fill out a raid. He should have been someone who gave us tips on this path to learning about Domination Magic or something. That's the sort of thing that feels bad when you reference an old plot or character. Bringing them back can be fine. It can be real payoff for a story. Pandering isn't just bringing them back, it's bringing them back for a quick reference that doesn't care about context.
Obviously we don't have the whole context yet, and that's why this is a concern and not a complaint, but I just think it would be a waste of all of Arthas' history and the way Uther and Pelagos have discussed it this expansion to just result in "generic evil raid mechanic".