After reading your article, I sparked interest and came looking for this forum lol. As I said earlier I didn't like it. I watched it a few months back and they made her look so non Elsaish and I kind of hated her more than I already did lol.

I want to share my opinion about this:

1. Your statement is true, that not all the princesses have been lovesick, like you said to Belle and Jasmine. But the other princesses like Snow, Cinderella, Aurora, and Ariel were lovesick after saw their princes for the first time. May be the video maker was thinking that all 6 famous princesses were always in the lovesick stereotype, instead some of them aren't. For Belle and Jasmine, may be because they have a happily ever after with their prince like the previous princesses before them.

2. The reason why Elsa singing the song because she is the way too much popular than Mulan, Tiana, or Merida. Besides, Mulan and Tiana were ended with marriage too. And Merida, probably because she doesn't sing in her movie (she only sung one when she was kid). Peoples think she is strong because she seems isn't kind of damsel in distress type, who always waiting to be saved by a guy, and she saves her sister instead.
I don't think she is weaker than Snow White. She is just a victim of her parents' rule that always told her to conceal her power. Indirectly it changes her personality, from kind and friendly person to shut people out. She was never given the opportunity to find a solution to the problem, so that's why she was always running away from problems. Because she does not know what she should do if she has a problem. Snow White is more lucky, thought she was treated like a servant but her life is more free so that's why she's more optimists and think positive.