When JetBlue added bag fees and switched to the three tier fare policy, they said it would be there. It even says so in the bag fee disclaimer:
1. For Blue fares, the first checked bag fee is $20 when purchased during web check-in or at a kiosk, or $25 at the check-in counter and the second checked bag is $35.
This is right off the JetBlue website. I say don't advertise something that doesn't work.