*Yes, I know some princesses don't fit these requirements, but they are often said not to deserve to be in the line-up, and for reasons included in the poll. You can take that into account or ignore it when you chose.*
I don't think this really affects the character very much. It does affect marketability to an extent, but I think the others do so more. And I'm not picking Princess by birth or marriage because I think the princess should be a princess OR the protagonist of her movie. But just my two cents.

People need to consider that just because they think that each princess should sing one song (I do too), does not mean that it is important factor in the COMPANY's decision. A lot of people are choosing what THEY feel is important without considering it through the COMPANY's point of view, so practically choosing to see what they WANT to see and not an overall importance.

This does not really matter much, since the princess formula is changing more and more (with less films being a musical), and this does not determine a reason why a character gets to be a DP. It just has little to no impact. Now that Merida is included, a lot of prior rules do not count, and you can't ignore it because it is only one character.

As I said, Mulan is proof. An honorary princess is just a princess as any.

Same reason as before.

Mulan is da bomb.com aka all other arguments invalid

I really don't mine Mulan in the lineup, and I wouldn't mind of Esmeralda and Meg and Jane are also in it.

It'd be good for Disney because little girls'll want to be princesses, but can't, so making normal girls do something and get made honorary princesses (Jane, Esmeralda, Meg) would be better than someone like Cinderella, who marries a prince, because seriously, how many princes are there nowadays anyway?

Okay I don't know which do go with. I mean Singing is the thing that needs to be in each movie. But the princess by birth or marriage. What if another princess pulls off a Merida move and doesn't have prince to marry but isn't a princess and then she joins the line up like that. I'm really don't know which do go with.