While the inclusion of iconic musical numbers like «The Bare Necessities» and «I Wan» na Be Like You» has varying results (although the former fits the more lighthearted tone of its sequence, the latter feels completely out of place), the animated version is defined so much by these two songs that it would have been a crime not to include them. (blog.bullz-eye.com)
Taking a much more lighthearted tone than the usual doom and gloom of Zelda proper, Tri Force Heroes» story is utterly forgettable. (attackofthefanboy.com)
While the happy ending fits the movie's lighthearted tone much better than this darker alternative, that might not be the only reason it was changed. (screenrant.com)