Alternative dialogue collection?

[Sagittarian]

Maybe it is just there for flavor and as a pause between long speeches?

Most if not all of the alternate dialogue is based on things the character has done, not on the response chosen. Like recognizing the character as an Azure Dragoon. People started pushing for it after around 2.2. There were a few places where it was really weird, like the lvl 50 culinarian quest has you cooking for the Sultana and she has no idea who you are even if you've finished all of ARR.