Why It Lands
Happiness Wins Over Looking Proper
Jane says this to a household that would much prefer she stay quiet and composed. She is not interested in composure for its own sake, and she says so without apology. The trick in the line is that dignity sounds like the nobler choice, right up until you notice it usually just means keeping your face still while you're miserable. She picks the messier, truer option instead. Most of us have a version of this choice on a fairly ordinary Tuesday: stay poised, or actually laugh at the thing that's funny. She'd tell you which one ages better.
A governess with no patience for pretending settled that argument a long time ago.