2 reasons:

- in a corporate environment, your code is going to be read by many other people than just you. Your team mates, the guy after you left etc.

- also, by making your code more readable, you're making your own life easier as well. You might have thought at first that your code was fine, but by structuring it properly and possibly removing some redundancy, you might find that you were overlooking some things.

In my experience code reviews are generally cursory and the emphasis on “readability” is more about a culture that seeks to treat programmers as fungible. Also complaints about APL’s lack of readability are never about its lack of structure. So I took “readability” to mean something else as should be clear from my previous comment. Is your complaint about its lack of structure? If so would you mind elaborating?