Reverse Thrust
Well I am an Engineer so here are my 2 cents;
Basically reverse thrust on Hi-Bypass engines are used ONLY for braking action during the landing. Airflow through the core engine is relatively cool in comparison to that part that is used for combustion. Turbine blades (not the rotating vanes) are internally cooled by that so called recoupe air. I am talking now about the 25% percent of air which goes through the core engine and not about the 75% (which is really cool air) going through the Bypass duct.
When reverse thrust is given while the engine has a certain speed, the RAM AIR Effect will provide enough air to feed the internal cooling system (LPC 1.6 Off Take on P&W Engines). If an Engine has no forward speed at all (standstill) there will be a lack of cooling air for the TBC (Turbine Blade Cooling) system and a thermal damage to the turbine section will occur.
The cascades on the Reverser halves are also pointed in different directions, also to create turbulence on purpose to those wingareas which normally create Lift. With this in mind several vectors of reverse thrust in different directions won't back the aircraft up, so it will only thermally damage internal turbine section.
During Testrun session we are only allowed to rev the engines up till 1.4 EPR for the max of 20 seconds. Considering the amount of thrust needed to back up a widebody, 1.2 to 1.7 EPR will be required which equals Take Off Power.
Ramp Rats won't be amused when containers and stuff like that follow them into their holes......
On the previous engine generation, internal airflow management was not such as critical as on nowadays generation. Also heavier materials were used at that time who could withstand higher temps but were less economical in inspection intervals.
There are experiments on the market for electrically driven tow trucks which clamps on of the main gear wheels and provide movement from the parking stand. The aircraft NWS (nose wheel steering) will provide directional control, but as in aviation every lbs is one too much, it's hard to believe that an operator will carry such an amount of weight on daily flights.
Happy New Year to everyone!