See also: What’s wrong with var x = new Array();
Aside from the Crockford argument, I believe it is also due to the fact that other languages have similar data structures that happen to use the same syntax; for example, Python has lists and dictionaries; see the following examples:
// this is a Python list
a = [66.25, 333, 333, 1, 1234.5]
// this is a Python dictionary
tel = {'jack': 4098, 'sape': 4139}
Isn't it neat how Python is also grammatically correct Javascript? (yes, the ending semi-colons are missing, but those aren't required for Javascript, either)
Thus, by reusing common paradigms in programming, we save everyone from having to relearn something that shouldn't have to.