I am positive the number of cancellations and changes performed by PLTs outweigh the number performed by general members...so they dropped lower tier fees and offset by charging PLTs...the 60 day rule is just punitive all around as UA knows availability will not be enhanced.
It goes like this...hey no charge to book under 60 days (if you can find availability), but we will charge you if you change it. AA hasn't outlined their 75K benefits yet, but I know even general members can make changes to dates for free.
I guess UA is trying to make some money back for all those status bumps they gave out this year!