In case you're being snarky: it doesn't logically follow that because PL notation should optimize for practitioners, that any notation will be successful. It's possible for a notation to be bad for practitioners as well.
There’s a small group of people (financial analysts, mostly) who use APL derived languages, are hugely productive and make tons of money, and have no interest in changing the language they use. Not every tool is for every purpose and not every language should try to appeal to all users.
Although many of the APL derived languages changed their syntax by removing the fancy symbols. I'm not disagreeing, though: some people like them, some don't, and that's why people use j, k, and APL.