The article where this thread is drawn from also goes on to state that the A380 was also given the same 10 nm requirement.... The FAA openly admits for the 787 it is an initial very conservative approach until all testing has been completed, including operation use at busy airports (as it was for the A380).
Too powerful? Only if the pilots don't know what they're doing with that power. Some carriers operate the 777-200LR with the GE90-115(B1L1) engines. Same fuselage as -200 models but with -300 wings. With a OEI situation, especially at T/O or G/A circumstances throwing the good engine to max thrust will throw that aircraft on its back, especially if at a light weight. Hence Boeing have a V2 floor for the -200LR (protected by a min Vref of 137 kts in the QRH) as well as a min take off weight to provide protection also.
(Hitting the TOGA switches once provides 2000 fpm performance. I can't think of too many scenarios where hitting the TOGA switches twice, or fire-walling the thrust levers to give MCT is needed).
See "The Migration to Higher Thrust Engines and the Effect on Control Speeds" by Steve Nelson from Boeing.