Completely agree that Python ought to be the default browser scripting language. Far, far better than JS. I've always been excited about the prospect of NaCl because it may be able to help us make that a reality in some limited contexts.
By this I refer to that in Python, most syntactic constructs map to more primitive operations that are accessible (and overridable) in the language itself. For example, anything can be made callable, indexable, sliceable, iterable, etc., by providing the right interface. It is like operator overloading on steroids. Even attribute access (the dot operator) can be overridden in extremely powerful ways. This is great for library writers, who can use it to provide the simplest possible API to their users.
Python's shortcomings are mainly syntactical (not counting the shortcomings of CPython's implementation specifically), such as not having an easy syntax for function expressions. This is the main reason functional programming can get slightly awkward in Python.
That's true, and definitely worth pointing out. I've used them a fair bit, and while they provide exellent power, they are slightly cumbersome to use compared to Python's pervasive "overloadability" (for the lack of a better word). But I would give them a chance to grow on me before passing any further judgement.
Yes, they'd have to come up with something else to get equivalent results from minification, like a special minified dialect where whitespace characters are replaced with another unused symbol (perhaps a canary-type header like the coding: thing). If this is determined infeasible they'd probably just have to accept that the whitespace needs to be transferred, which honestly I wouldn't really consider a bad thing.
Minification should not be considered as a major reason to forgo the benefits of alternate scripting languages.