If you change the pots to 500k you'll get some treble bite, thats why almost all manufacturers use them on humbuckers, and put 250k on single coils to tame a bit their shrilling highs.
That's what "they" say, just like "they" say to always use audio taper pots. Yet Gibson has used 300K linear taper volume pots on its humbucker guitars for 35 years now. And the series humbucking split Precision Bass pickup uses 250K pots and has plenty of treble. Go figure.
Fender voiced this guitar to sound a certain way, and they used 250K pots to get that sound. It wasn't a mistake. No doubt the guys on Harmony Central know better, all because the mysterious "they" say to use 500K pots with humbucker.
Maybe, just maybe, the manufacturers know to use the pots that best fit the frequency range of the pickup.