Night Kingdom isn't going to be "Adults Only." It will be open to anyone who is willing to pay for it. Discovery Cove is the same way.
I don't know why everybody is so up in arms over Night Kingdom. It's a boutique park that has worked extremely well for Seaworld. Disney has every right to try and create a different demographic, that being a more affluent, "experience" oriented audience that doesn't want "rides" or "shows" but an actual experience.
People are freakin' out because it's going to have a rock-climbing wall. A lot of people enjoy rock climbing. "If they want to go rock-climbing, they can do it at home," they argue.
If they want to go bowling, they can do that at home too. But no one seems upset that Disney is building a bowling ally.
I don't know what people are expecting from Night Kingdom, but I can tell that they aren't comparing it to the only comparable thing in existance: Discovery Cove. Stop thinking of Night Kingdom as an expensive AK and realize that there is a ton of potential in the concept.