The Olympic Committee specifically asked for bids that emphasized no-budget-blowouts due to many previous Olympics essentially bankrupting cities and the bad rep that was causing to the Olympics brand
That's true, but the criticism from people opposed to the Olympics is that this was purely a PR exercise and that in reality there's no serious effort being made to avoid budget blowouts and huge spectacle just like previous Olympics.
Personally, I think this aspect is somewhere in the middle. It's not going to blow out as much as past Olympics have, but nor is it being done up to the best hopes people had when hearing the intent of a lower-impact Olympics.
and Brisbane’s bid was the only one that stacked up to scrutiny
I think Brisbane was the only one that really even tried to put in a serious bid. Nobody else really wanted to.
I think the Gabba is a special case. They have been wanting to expand/fix the Gabba district for ages
Definitely true. But I'm not sure people were expecting a complete demolition and rebuild, followed by more major refurbishments post-Olympics. Is the entire rebuild necessary regardless of the Olympics? I don't know enough about stadia to say.
the two 4-lane roads on either side that the back of the stands over-hang has been a problem forever
True, but I don't think there are really plans to fix this. The new rail (CRR) and bus (Metro) options are nice, but the whole area could use some major road dieting too, and as far as I'm aware that's not on the cards.
link it up with the river better
Unfortunately without that road dieting, walking and cycling are still not going to be very appealing options from the Gabba. It's certainly possible to link up with the river currently, but it's not pleasant, and none of the proposed changes I've heard of will change that. I will be very happy to be wrong there though.
they will probably use it for big concerts and so on
RIP Taylor Swift fans.
and natural tourists attraction
For sure. I could not agree more with former Councillor Jonathan Sriranganathan when he says "we should start by recognising that we are already Australia’s greenest major city. This is a key strength we could build upon as the world’s eyes turn towards us." (while I disagree with his stance that we should simply not have the Olympics at all). Our greenery and wildlife should be what Brisbane leans into in creating its "brand" for the Olympics.