"They are only licensed for use with genuine FTDI parts. If you don't like that get your own drivers"
That's actually a big question I'm having for years. FTDI essentially makes devices compatible to the USB standard for "serial ports". Just about any operating system has default vendor independent drivers for that, after all that's one of the few bits where USB is actually standardized. The only exception is Windows. If Microsoft would get off their asses and finally support USB in any meaningful way this whole mess wouldn't be possible.