It's a agree to disagree thing. I think Tiana is a very loved character and the potential for story is there, even in a shoehorned Splash. However, my opinion is that I think the ride system itself is wrong for Tiana.
If you're wanting to make a statement about inclusiveness, I think it really should have been a Pirates-type ride, that includes people below 40 inches. With Splash, families with small children will have to broken up and ride separately, which is a large portion of guests when you think about it.
With a new ride system, it could have been designed to allow families to ride together, with some thrills still tucked in there. An inclusive ride, inclusive for the whole family. It's not just the message the ride has, but the message the ride system conveys.
Personally, I think it's a huge missed opportunity, plus a park like DHS could have really benefited from a New Orleans Square type area.