Hokay, this is going to get kinda long...
Roo meat has plenty of pro's but a few con's too. The aboriginies didn't subsist on it, they ate it at certain times of the year when the animals carried more fat. Roo is exceptionally lean (don't even bother trying to cook it past medium rare unless you're going to stew it) so you need to compensate for that with your meal. I'm hoping someone with a good link to nutritional values will jump in here because I know it is stupidly high in K? or something, which can be a problem.
Roo meat was once seen as a cheap pet mince here, as a by product of culling and the fur trade. (Yes, culling is very necessary in places.) It was not seen as a food for the dinner table because, let's face it, who wanted Skippy giving us the guilts at 4pm on the kids' channel? This attitude changed and you could buy it prepared at a stupendous price in a tourist restaurant, or at about a quarter of the price of beef at the market. It was then trialled at the supermarkets in vaccuum packs and failed to attract a market.
There was enough interest that the fresh markets attracted more of a following and better cuts became available. You wouldn't see them on show but if you asked the right guy you got something better than dog food. The following grew, produce once again made it to the supermarket shelves and now we pay $20kg for roo fillet, $30 for beef eye fillet or lamb backstrap. Market pricing varies, of course.
One of the issues is our inability to control the level of nasties in the carcass. We don't control the feeding, they're not vaccinated and people get scared. Roo is not allowed to be hung in the same room as farmed meat. This makes it impossible to sell fresh in a butcher's stall.
The flip side to this is that the pasture varies wildly. Noone's going to let a mob of roo near their prized canola or wheat. Not without a fight, anyway. This means they get a varied diet and they generally eat the parts of the plant they need. This can be tampered with to some degree, of course, but you're never going to force finish them on a diet of junk food and corn.
Culling is done as cleanly as possible but you're never going to find anything hunted wild killed 100% humane. Hell, abotoirs have enough trouble staying the right side of everyone even in this country. You're never going to have a completely clear conscience unless you're prepared to kill your own meat.
I'll add that I'm no expert in the field. I'm Australian, I've nursed and rehabilitated roo, I've created places where I can have mother and joey pull at grass next to my windows unafraid. I am also a great fan of roo meat as a part of the Australian diet. For environmental reasons, for health reasons ,and for economic reasons. More importantly, because it makes the best damned hungarian goulash you've ever eaten.
PS Too much roo meat is bad for dogs and cats. Balanced diets are not just for sheeple.