I suppose because an outfit implies something like a suit or set of clothing worn together, whereas "clothing" can mean any clothes, skirts, dresses, trousers, nightwear, underwear etc etc.
"My mother likes the wear" is not correct as an English translation. "The wear" isn't an English noun.
It says "likes the clothes". I suppose the plural of cloth as in Kleidung was Kleidungen. Any corrections?