Yes, indeed. I didn't mean "legacy" to imply that they aren't still useful. Simply that many of them predate the creation of codepoints which don't fit in 16

Yes, indeed. I didn't mean "legacy" to imply that they aren't still useful. Simply that many of them predate the creation of codepoints which don't fit in 16 bits -- and it's harder to upgrade a binary API distributed in a client OS, compared to changing a web server's preferred encoding. JS/JVM/CLR all work fine, but I imagine if they were created today, their strings would not be based on UTF-16.