well, I think you’re right in that that was the idea behind the transformation and that’s definitely how their romance blossomed :)
I think sometimes it’s good to keep in mind that often stories only seem like they “have to be this way” because we’ve become so accostomed to thinking of one version as the only possible version. Is there really only one way, though, to get a character to fall in love with another character without focusing on physical appearance? What if some plot device had simply made him unable to see her? Or what if there was a magical spell that made them both see frogs, yet the viewer could (when not looking through their eyes) still see them as human? (ew it’s like the plot of Shallow Hal, but ok, it’s just theoretical.)
Also important to keep in mind is that the plot never had to go that way in the first place. Could there have been other ways of making us realize the importance of beauty on the inside without making Naveen like… a player first? Probably. A fair amount of movies have used the “realize the love interest’s inner beauty” theme so there is precedent.
Another thing to note is that racism doesn’t have to be intentional in order for it to exist or be a problem. Even if it’s completely accidental that the first black princess is a frog for a good portion of her movie, and not the result of a conscious or subconscious effort to keep her human for less time out of a presumption that a frog would be more appealing to white audiences than a black girl, does it really matter when the end effect of it all, the effect that young, black girls experience, is that:
the only black princess is a frog for half her movie?
My own two cents as well is that the “see true beauty” card is incredibly overplayed in tv and movies and to some extent tries to manipulate us into not examining the deeper implications of characters and plot. I fail to be impressed by this theme so long as the characters conveying this theme still always manage to fall within a pretty standard idea of conventional beauty.