I've worked in the kids club at
DCL, and currently work in the club on another line.
Sure the DCL clubs can get chaotic and often look worse than they are because they're so open, and there's almost always an active game going on in the main floor.
You don't get many kids older than 10 as they can go up a group at that age. Often you'll find that the older kids are either looking out for or actively avoiding the younger ones. CM will actively engage or distract the younger ones, I would often walk the younger ones to something more appropriate, even if that meant taking a stroll over to the other room.
Do kids get hurt? Yeah, they're kids! They don't watch where they're going. They don't have the best judgement. They get stuck into games. But it's not every kid, all day every day....in 4 years at disney, the only time I remember a kid purposely hurting another kid it was when their sibling broke their craft...
You can drop off, keep phone with you, sit on the floor outside if you have to and you'll be there within in seconds if your kid asks for you or to leave. You can go and check in as much as you like.
Let your kid have a chance, sometimes they need a break from the family and just need to be wild and run around, or sit and watch a movie with other kids, or dance around with the characters. But if they hate it, you can at least say you tried.
Now, like I said I work on another line. Last cruise I was in the 3-5 age room. I would have the same 9 kids (there were only 12 for the age group onbaord) come to every session, by day 2 we all knew each other so well. I knew that child A was obsessed with colouring and which pictures she had already done, I knew which movie had to be on just so child B would come through the door, and I knew child C would come in crying, need 5 minutes in the corner on their own and then love the session and not want to leave. With all this, and such a small ratio, I still had to fill in accident forms, one kid ran into another and they bumped heads and another head butted a table while doing some crazy dance move.
What I'm saying is you can have a room with a handful of kids all the same age and size and they'll still get hurt, or cry. They can love or not love the time in the club.
Sure, some kids and the club just don't fit. But the club's also give opportunities and memories that they can't get anywhere else.
(If you want to avoid the crazy times then from what i remember avoid around 10-1 on a sea day morning, or the all aboard times on port days)