Government - What's it good for?

Here's a fundamental question, especially in a country that has just gone through elections - what does the parliament do?
You can see that the title I used above is different. At first, that's what I was thinking - "government" - but then I realised very quickly that I didn't mean those that don't get elected. There are public servants, appointments, etc, who get on with the job they were expected to perform (to some degree) with interference only from those that we, the people, elect.

What has evolved as a parliament has a strange history from the two conflicting needs to counsel the monarch & to ensure that the monarch doesn't overstep the rights of the people. Here, of course, "the people" were those with property & money, with things at stake.
As soon as you have reviewing the monarch, you end up with a monarch who is always trying to test their limits, & thus parliament becomes a shaggy dog.
Essentially, we can't get rid of the one we've got. It's also grown since its inception to take over the roles of many other political functionaries.

Direct monarchy doesn't happen in Australia, & even the Vice-Regal has very fine teeth. Therefore, the parliament isn't counselling anyone - it seems to be a self-perpetuating process of navel gazing, that is, reviewing itself.
This is all well & good if it had well-defined functions on which to base its review. It seems to be there just "to rule".

Other things that happened to Australia is the true separation of Church & State, & a theoretically independent Judiciary.
The latter is not quite true, because the laws (the Queen's Law, in fact) come from the parliament.
The interpretation is left to judges, whose experience is relied on thereafter - unless the parliament decides to do something about them as individuals.

There is no Church. There are some left-overs from a once-Anglican dominance (we talk of parishes within an electoral boundary), but there are now so many churches that there seems no relationship between any one of them & a given parliament.
This, to me, means two things - there is no social cohesion on questions of morality & ethics (or even debate), & the parliament thinks that it should step into the gap (heaven forbid!).

I think gay marriage is a classic example here. Why does the parliament decide on the social representation of people's relationships?
Can a church not recognise & perform gay marriage within its separate articles? How can a parliament then say what marriages that church can perform (or will be "recognised")?
Australia is a special case where de facto relationships are already recognised by the parliament (& the government) as equivalent to marriage.
How can the parliament interfere with a church in that way?

If a bunch of ordinary people elected to create laws (or review them) is given the power to determine what a church can do - or the judiciary - then they have too much power, & surely we should have some kind of review on that process itself to ensure that the parliament doesn't overstep the rights of the people (not just those whose support got them there).

This seems to be going around in circles - meet the new boss: same as the old boss.