I'd say the easiest way to remember the argument order is that it's conceptually the same as for mv and cp: ln -s x y is the closest possible symlink-analogue of cp x y.
Ah, I remember it is the non-intuitive one, but then when I use it a while, I keep double-guessing which one is the intuitive one.
Kind of like when my wife tells me I'm doing something wrong and she wants it to be the other way.. I know she thinks this thing is important, but can't work out which way she wants it done.
I remember this as "ln=long -s=short $long $short" as in "ln -s $long $short" creates a $short file pointing to $longfile. But to your point, $short is defaulted to basename($long).
