How much did American admiration for Japan matter?

How much of the disastrous early Pacific War can be blamed on American Japanophiles?

Not much: the initial underestimation was real, but combat experience corrected it quickly.

American forces initially underestimated Japanese torpedoes, aircraft, and ships. Combat exposed the error, and reports from survivors quickly changed later assessments. The mistake mattered, but it cannot explain the early Pacific disasters on its own. Direct battlefield evidence forced the US Navy to revise its assumptions faster than old stereotypes might suggest.