I think both sides are wrong (Score 1)

The reason the most manufactures use the FTDI driver is because most windows systems already have it installed. This makes it easier for consumers because they don't have to track down a driver from some unknown source. But it is well within FTDIs right to change their driver as it fits their needs. The solution would be for their to be a standard driver that manufacturers could use for usb to serial communication just as there is a standard mouse and keyboard driver for usb devices.