BTW, I've been 3000' plus by the departure end of the runway in a light BUS before
All this is nice and well but the brake issue calls up a large number of things. The MAX autobrake will stop the aircraft damn quickly upto V1. The problem at this stage is then brake heat dissapation due to the fusable plugs in the gear blowing at around 800-850 degrees and giving you the added bonus of flat tyres. Brake fans, hubs and tachometers don't stop the brakes being applied upon retraction to stop wheel rotation, this is supplied from the hydraulics (through the yellow system I believe i.e. the parking brake system). A defective tachometer or missing brake hub will not supply wheel rotational velocities to the autobrake system due to the fact that the anti-skid believes the wheel to be stationary and therefore would not apply any braking to it anyway.
Carbon brake discs work better at high temperatures but have peak brake wear between 200-300 degrees therefore the brake fan policies of many companies.
The case here of the gear left dangling is purely for cooling reasons and is called for in the minimum equipment list (MEL) for specific dispatch with missing or failed components. Bizzarely the wheels keep very warm even during a long transit and dispatch with high brake temps will give you possible problems when operating to a performance restricted runway (short!).
Hope that helps.
This requirement is only there for the cases where the brake temperatures are not visible on ECAM and the brake temperatures have been calculated from the performance manual graphs. Belt AND braces
