> their main drawback: k/q (like clever regexes) are often write-only code
This depends on the code reader's mentality. One line of k (or q or j or apl) would do what 10 lines of verbose languages do. For verbose languages, your expectation is spending 1 minute for 10 lines of code to fully understand it; but for terse languages, you need to change your expectation to spending 1 minute for only 1 line of code. You are not going to understand anything if you still want to spend 6 seconds per line.
On the other hand, proficiency is important. You read English articles in a slow pace in your first grade; you are not going to be a speed reader without practice, even if English is the only language you speak. No one would expect you to speed read Japanese right after you can compose simple Japanese sentences.
On the other hand, proficiency is important. You read English articles in a slow pace in your first grade; you are not going to be a speed reader without practice, even if English is the only language you speak. No one would expect you to speed read Japanese right after you can compose simple Japanese sentences.