Wow, someone is itching for a fight.
I am not saying its right. Its shady as hell, immoral, etc, but its not illegal. Look at the "fees" that companies like comcast and others tack on to peoples bills.
Again, you could try and argue to a judge that you should be allowed to "opt out" of that increased withdrawal fee but you don't have a leg to stand on. By your logic because you deposited before a certain date you should also pay the original trade fees instead of the 0 fees now implemented.
In short, we aren't entitled to anything. Making a deposit to an exchange is NOT a contract for a purchase or business deal. The date of the deposit doesn't matter in this instance because there is nothing to opt out of. You can try requesting they close your account and send you your funds with no added fee because you don't agree, this is the only way you have a chance of "opting out". Again, its shady as Fck and we need regulation in crypto despite all the libertarian free market BS that keeps getting spouted.