I think it just comes down to:
1. Whether or not others agree, Disney decided it didn't want anything tied to SOTS in its parks, and for that reason, Splash Mountain had to go.
2. Tiana was a logical replacement, given the setting of the film and the setting of Splash within the park, a growing fan base for the original film, and a property that sends an inclusive message-something SOTS pointedly has not had according to many people over the years, including at the film's original premiere.
As much as some people have clearly enjoyed going into Conspiracyland when it comes to this project, I really think this is it.
Occam's Razor very much applies here IMO.