Yep Serfty. I agree "illegal" was the wrong word to use (which is why I added reference to T&C). Your version is much better

My point being, of course, that it's a violation of the T&C to sell points, even if it's pretty common to do so. In theory buying such points could get one's account wiped/suspended so then the value would be.. very bad
as for QF restricting availability in certain cabins on certain routes.. it's called yield maagement. Why does QF make availability so difficult on HNL-SYD? Because they call sell those seats. Plain and simple. And sure, there are other (often better) options in multiple markets, but that assumes one has the resources (points, dough) to access those.
The other thing, there are often more ways to get to where one wants using points if the direct option is not available. Yes, it's a PITA, but airlines are not going to give up FF seats when they feel they can get higher yield from paying pax.
In a somewhat related note, it's interesting to note that in the USA, Delta used to be like the others and most of it's domestic cabins were full of "free" elite upgrades. That amount has shrunk a whole lot because DL wsed up and started offering F "upgrades" or discounted fares at far more reasonable levels where they could extract a premium on the Y fares they would usually have gotten for those pax who did not want to run the elite lottery and would consider an extra $100 (or whatever) fair to ensure that seat up front vs the much higher amount it was previously. AA's version of this was the Y/KUPP fares and UA had similar.
In turn, those product offerings reduced the value of the elite status for those who saw it as a "free"(but not really) means of getting into a premium cabin.
The US majors also have faced product competion and pressure from the likes of Mint (jetBlue) which is a better offering than mostly what you'd get on the legacies, for a (usually) lower price point.
now QF/VA do not do the comp elite upgrades like in the US, so it's very different here (minor exception being the spuriously seen P1 comp upgrades, which I've had a few, and others have had too, but it's way more of a courtesy than a defined benefit like in the US programs). As such, for those that want to sit in the premium cabins, either you pay with cash or points - which is how most of the world does it.
Anyway, value's where you find it and sure, if the goal is to get 5 people to Hawaii in J, then you'll probably feel little value exists... however there are still value options to be found but it's obviously very subjective based on each members personal requirements/needs and what they are able to secure.