So says Guy Steele, one of the Java stewards at Sun. In explaining why Java doesn't support closures, he said:

Java does not support decimal arithmetic well, nor classic coroutines, nor full IEEE 754 floating-point arithmetic, nor computed GOTO, nor Fortran-style (or Common Lisp-style) FORMAT operations, nor automatic backtracking, nor pattern matching, nor unification of PROLOG-style expressions, nor tail calls, nor a host of other features. I've been beat up pretty hard over some of these. Some of them I even argued for myself in the early days of Java (such as tail calls). But others simply aren't needed for the clientele Java is trying to serve.

That last sentence is, to my mind, telling. Especially in combination with how Joshua Bloch described that clientele to me (the lower two tiers on a pyramid).