Their excuse was that the exchange rate is too unpredictable to risk adjusting their prices... as in, if they drop their prices at Toyfair one year and the exchange rate suddenly plummets, they lose money on the prices they've locked in with retailers for the next 12 months.
Basically they claim to be shielding themselves from an exchange rate that could not occur in the space of time between Toyfairs, without a total collapse in the concept of capitalism (or a depression)... And if that happened, selling toys would be the least of their worries.
At least, that's their excuse... when in reality, it's just the result of them getting fat of the increasingly widening profit margin. Charging 3 times the price Hasbro America charges their retailers, means 3 times the profit... and the retailers here just have no clue they are being scammed. (or don't care)