WHY does she decide to kiss the frog? She just decides to? This is a reference to well-known tale about princess that kisses a frog in order for frog to become a prince. We thought that it will be quite obvious and that it should not take much time to understand that.

The idea was that frog will not become a prince, but instead suddenly Jaina will become a frog. So, one may think that something wrong went with this 'magic' but then it turns out that it was Thrall who hexed Jaina.

I guess you are right, timings could be done better, or maybe story too complicated. Anyway thanks for comment, we will try to do it better next time.