User blog comment:Videogamep/Should the Anime be Seasonal?/@comment-53507-20151115062016/@comment-2226235-20151115071248

The main reason they can't/won't is money. One Piece makes a huge amount of money both from ratings and from merchandise sales. A lot of the merchandise companies are what funds the anime, so a hiatus would lower sales. This kind of thing always comes down to money.