These things never happened in the old, classic 747's
No, they never did:
Air India 747
KAL 747
Air China 747
As for the thrust going to climb power it freezes at the setting just prior to disconnect, with the Thrust Lock function
There are failure modes, including inadvertant disconneciton, where they do run to full (CLB) power.
...and the boffins who design these modern marvels need to make sure the pilots retain the authority and ability to recover an aircraft in distress.
How can you conclude the "boffins" have not made sure of this in the AF A330 crash? In the TC incident, they had the ability (but "chose" not to use it) to control the aircraft. As the above links show, the "boffins" add these protections in an attempt to increase safety. Some of the above accidents could not occur in the same manner in a FBW Airbus...
I am not overly for or against the Airbus v Boeing philosphy - I have flown both. But until we get a full analysis from the BEA, it is hard to see whether the FBW "laws" were a (significant) factor.