I was on this flight. Didn't seem a real big deal to me.
Essentially we were all seated and buckled up, the captain came on the loud speaker and said they couldnt release the brake to commence taxying and engineers were looking into it. About 15 or so minutes later, they thought they had narrowed it down to an electrical problem, but were waiting for an electrician to come out.
After the hour was up, the flight was cancelled. I have never seen a 200+ deep queue at the service desk to get rebooked. Thankfully I was sitting in the front rows of economy, and managed to get on QF414 at 8 am, although my luggage never made it with me and was delivered directly to my hotel after consultation with Qantas baggage services in Sydney.
I don't recall anyone being offered a choice of going onto the tarmac to go find their own bag though, so if that did happen it would of been after I had already been rebooked.
Would rather they find a brake problem on the ground than in the air.
Was a bit disappointed with one of the male flight attendants though. Someone was standing up talking to a pax in the row I was in, and the male flight attendant walked past and snidely remarked "we care about your safety remember". All the pax in the row just looked at each other with a "wtf" look. I guess the flight attendants must be getting sick of the issues themselves, and being on the front line they'd be copping the brunt ala branch staff at Commbank after the latest rate rises.