I really don't understand the need for the increase in the fees as there is no reasonable justification for their actions. Mining fees have dropped significantly, timing confirmations have equally dropped. The height of it is little or no regard for their clients by not giving any notification and that is why regulations being clamoured for will always have their way. A company does not just go ahead to increase its fees without carrying along the regulatory authority just as banks will not wake up and charge arbitrary ATM fees, COT, alert charges, without recourse to the Central bank and notification of the customers.
4x is just too high and there is need for those using the platform to start considering alternative means of carrying out their transactions because their thinking is that earnings from cryptocurrency is "free money" and you can afford to pay any associated fees that comes with it. Accepting that and continual use of their services will only confirm their hypothesis and a justification to do 10x in the next review.
I have been thinking further about this, and sure, you are likely correct that smaller players will likely vote with their feet - however, bigger players might not. Gemini had already chosen nearly fee free (or no fees) to move money from your bank to and from their service, and probably that choice has caused additional costs on Gemini - and therefore some of their users likely have been using Gemini to get in and out of bitcoin - however, surely their choice to 4x their fees on April 2, and they had 2x their fees 6 months earlier, which is more than 10x in their fees. Gemini is going to measure to verify whether they are retaining enough of their BIGGER and likely desired users in order to off-set the smaller average Joes that they are losing by making their trading fees about 4x higher than other exchanges (their bet may pay off if there is not a lot of competition for BIGGER players to get in and out of the space, and some of the BIGGER players might prefer Gemini, even if Gemini's current liquidity does not seem to be as large as some of the other exchanges).