This is because these font files originate from a Microsoft initiative called "Core Fonts for the web" that ran between 1996 and 2002. Before web fonts became a thing, Microsoft wanted to make a set of broadly available fonts that web designers could assume everyone had on their computers. Because Microsoft cancelled the initiative, the redistributable versions of those fonts are stuck in time. They were last updated around 2000, and any updated versions with further improvements or added characters aren't freely redistributable.