I absolutely agree -- I never said that learning new languages is useless -- it's just that there are other things you can learn that are much (much) more useful.

For example, decent familiarity with various algorithms and data structures (the more the better), OS architecture and hardware architecture will also improve your skill in every language, and will do so to a much greater extent than knowing Lisp, Haskell, Prolog and Python. The reason is that different programming languages differ in the abstractions they provide and the way they're used to express algorithms. But abstractions -- while very important -- are secondary to the algorithms themselves.

I'm saying this from the vantage point of roughly 20 years of experience, after having learned (to varying degrees) Lisp, Haskell and Prolog. Yes, they help. But knowing that other stuff helps so much more.

I find that it is younger programmers who tend to equate a program with its code, while more experienced programmers learn to separate the two: the code (which is very important), and the program itself -- the stream of machine instructions that get executed on the CPU and its interaction with other hardware subsystems and the OS. Today I can get a very good feel for what a program does -- and how elegantly it does it -- without even looking at the code or knowing what language it's written in, but simply by running it in a profiler (or several), although the profiler should be appropriate for the language. I find that "profile elegance" is even more important than "code elegance".

Code elegance is sometimes subjective and is almost always language dependent. Often, migrating abstraction concepts from one language to another really hurts code elegance; chief among those offending imported concepts is the monad, which has much better alternatives in imperative languages -- in fact, I'm giving a talk precisely about that in the upcoming Curry On/ECOOP conference in a couple of weeks.