In To Kill a Mockingbird, Harper Lee characterizes Miss Maudie Atkinson as a "chameleon lady":
a chameleon lady who worked in her flower beds in an old straw hat and men’s coveralls, but after her five o’clock bath she would appear on the porch and reign over the street in magisterial beauty
So, Miss Maudie is a kind of Earth Goddess (Mother Nature) who blends in with her environment. When she is outside, she blossoms: she is vibrant, outgoing, and radiant. But when she is inside, she withers: moody, depressed, and lethargic. She is a kind of foil for Boo, who works best in the shadows.
When Maudie's house burns, she is not terribly shaken. Instead, she sees it as a time to spend more time in her garden:
“Always wanted a smaller house, Jem Finch. Gives me more yard. Just think, I’ll have more room for my azaleas now!”
...I hated that old cow barn. Thought of settin‘ fire to it a hundred times myself, except they’d lock me up.”
...Why, I’ll build me a little house and take me a couple of roomers and—gracious, I’ll have the finest yard in Alabama. Those Bellingraths’ll look plain puny when I get started!”
So, Maudie uses the house-burning as a means of downsizing her "cow barn" and spending more time in her yard.