According to my TA not only did all the airlines raise the fee to $100 but lowered the fee paid to TA's to $15. So for the airline who doesn't do anything in the transaction they will receive$85 instead of $75.
Of course the real reason is to force those who are making changes on a regular basis to buy a higher price ticket. For the person who might have something come up once in a blue moon it still makes sense in my mind to purchase the low-cost leisure ticket and take the chance. In all my travels only twice have I had to change a ticket - both times with DL - once they waived the fee and the other time they charged me.