The US Constitution is not much to be jealous about. In Australia, if people are unhappy with laws, they can change the government, who in turn can change the laws. Meanwhile, in the US, the validity of laws is decided based upon the views of unelected bureaucrats appointed by past Presidents.
The US has the highly undesirable situation of (1) the possibility of a deadlocked President (because Congress does not support them) (2) the possibility of a deadlocked legislature (because SCOTUS doesn't support them).
The Australian Constitution completely sidesteps these conundrums. A bad PM can be ousted in a day. The High Court avoids getting into Constitutional rights disputes except in limited circumstances, such as undue burdens upon the implied freedom of political communication. I consider this significantly more desirable and the US offers nothing to be jealous of.