Well, the core issue is that there isn't a standard vendor-independent device class driver for CDC devices in Windows like there is for say HID. This is a solved problem on pretty much every other OS. The only reason a manufacturer would make devices that use the same vid as an FT232R as opposed to a functionally-identical pin-compatible device with a different vid is because the drivers included in Windows are vendor-tied. You don't see this kind of issues with no-name mice or keyboards for example because they don't need a vendor-specific driver.