[taneq]

The problem with 'expressiveness' is that beyond a certain point, the cognitive load imposed by reading the code exceeds any benefit from the increased density and abstraction. You basically have to decompress the code in your head in order to comprehend it in any useful way.

[TeMPOraL]

Only if it's written so badly that it leaks, or you need to modify that particular abstraction. In all other cases, you should be able to read the code easily and understand what it expresses without the need for exploring underlying layers of abstraction.

I agree it's hard to write good abstractions, but the problem isn't really in Lisp per se - it's just that being able to express any abstraction you want cleanly makes you realize that coming up with correct abstractions is very hard mental work. You may refrain from doing it, but Lisp at least gives you the option.