I had this same issue and attempted the same fix, which worked but i also noticed another issue which is not mentioned here. All the ini files had been set to read only by win 8.1 which prevented any changes till I removed the read only attribute, I was then able to make the changes to the suggested settings to start the client, but was then unable to save any change to settings in the char specific interface, it says they were saved but then reset to the old settings after logging out of the game. After checking I noted that all my char specific ini settings files had the read only attribute set as well, so i removed this to see if the char specific settings would stay changed after relogging.
After removing the read only attribute from all the ini files I am now able to change and to retain the saved changes for each char after relogging. This needs to be fixed as many will not know about the read only attribute being set by windows.
The one thing I am not sure about is where this change came from whether it was windows 8.1 or the patcher which made the change to the file attributes but I suspect it was the patcher as I did not have this issue before a certain patch (cannot remember exactly which).