Life lessons from Uncle Iroh --- Even though he's not real, Uncle Iroh has some of the greatest quotes ever:) As I read these I swear I her uncles voice in my head. No one can give advise and wisdom better the Uncle Iroh.
It makes sense though. In the (which Legend of Korra is assumed to be set in) the first real swimsuits were made. In Avatar the Last Airbender they didn't have a defined swimwear so they wore whatever.