"well in the movie they were good, they only helped people and played"
I think the trolls were bad and I felt hans significant character shift is better explained by troll magic than bad story telling.
Fun read though!
Gad would have just finished up with BoM when they started doing voice recordings for frozen. Knowing nothing about the background, I'd bet gad was a pretty late addition to the cast.
Knowing Disney, they are trying to make Gad the new Robin Williams. If you look for the advertising around Frozen there is a TON of focus on Olaf even though his role is really minor in the first movie.
Same thing happened with Aladdin and the Genie.
This part of the song is particularly telling:
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So she's a bit of a fixer-upper, that's a minor thing
Her quote 'engagement' is a flex arrangement, and by the way I don't see no ring!
So she's a bit of a fixer-upper, Her brain's a bit betwixt
Get the fiancé out of the way and the whole thing will be fixed
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With that said it doesn't quite jive with Hans' betrayal (you could argue the Trolls made him do it but there's no support for that claim). But I think there was a potential to find out that the Trolls were manipulating things behind the scenes to get Kristoff and Anna together.
I thought this article's theory might help explain the Hans weirdness, but now I'm just more convinced the plot is a mess.
It is much more simple and plausible explanation, "they were wrong" then trying to make ma big manipulation.