I've heard it said that it becomes easy to spot common patterns and structures in this style. Without knowing the idioms it's difficult to read but apparently once you know the idioms, you can scan it and understand it well.
It is for APL/k/j; you see patterns popping up in very dense code which does a lot, which does make it readable really once used to it. But most people never get to that point (or even ever look at APL of course).
