I don't understand why people go to Dubai for these things. Similar things exist in the US and are likely cheaper, before even thinking about flying halfway across the world. It perhaps makes a bit more sense if you're coming from European winter.
Those attractions probably get a ton of business from people on short stopovers. I can't see taking my family just to Dubai, but I can totally see using it as a stopover point on the way to Asia and letting the kiddos splash around in a water park while we're there.
I *could* see doing a 1-week Dubai / Oman / Abu Dhabi trip someday, but there are still a lot of things higher on our list, both with and without the kids.