Back to 2015 it wasn't "upset a lot of people". The ones who wanted to mod their game just switched settings. File check was part of checking game version system to prevent reconn errors I guess, because sometimes 2 copies of YR game v1.001 installed from different installation packages was giving a reconn error. Since CnCNet Client usually changing game files a lot I suggest you to avoid keeping your unique mod files in this game folder, becasue you may lose them in any moment if you have auto-update enabled.