Finance uses it because it's great for sorting out medium-big time oriented data. The IQ test aspect of it is probably considered a bonus in some shops.
There are non-terse APLs out there; the most obvious one floating around is Nial[1]. Culturally though, once you've figure out how to read and write in the compressed ascii runes, it's kind of hard to go back to the other way. J is actually denser because of the hooks, forks[2], rank and full tacit aspect of things. Personally whenever I've composed an algorithm in J I feel like I really understand it in a way that pretty much nothing else gives me with all the extra typing.
There are non-terse APLs out there; the most obvious one floating around is Nial[1]. Culturally though, once you've figure out how to read and write in the compressed ascii runes, it's kind of hard to go back to the other way. J is actually denser because of the hooks, forks[2], rank and full tacit aspect of things. Personally whenever I've composed an algorithm in J I feel like I really understand it in a way that pretty much nothing else gives me with all the extra typing.
[1] https://github.com/danlm/qnial7
[2] https://crypto.stanford.edu/~blynn/c/apl.html