The following conversation is precisely why:

“Puffed sleeves are so fashionable right now. It would give me such a thrill, Marilla, just to wear a dress with puffed sleeves.”

“Well, you’ll have to do without your thrill. I hadn’t any material to waste on puffed sleeves. I think they are ridiculous-looking things anyhow. I prefer the plain, sensible ones.”

“But I’d rather look ridiculous when everybody else does than plain and sensible all by myself…”