:::Why is there "so much" about USC-2 here?  (There's really not very much.) Because UCS-2 redirects here, and this is the natural place to describe it, since it is the basis on which UTF-16 was built.  It's fairly clear from the article that UCS-2 is obsolete.  We can say that explicitly, say by adding the following at the end of the first paragraph of the History section:  "UCS-2 represents an early, incomplete, and now obsolete version of UTF-16 that is limited to the codepoints that can be represented in 2 bytes."