And again, you show you have no clue how these "clones" work. They are not defective, the driver on the other hand is... and they admitted this was their goal already so stop bothering to defend them. They lost and now they have to pay for the consequences. I can also tell you that most designers I know have already stated that they will never use FTDI hardware ever again because of this: so not only did they enter very slippery ground in a legal context, they alienated the engineering community.
And then there is another issue, after this one FTDI deserves to die. They broke the gentlemen's agreement within the electronics community about interfaces and bus systems. Bus systems can be patented (see IC), but you should never use that patent in an offensive way except if people are conflicting on your address assignments or are going "too far". Either way, this case does not apply here because we're looking at interfaces, and those are considered free-for-all. Its very common for IC manufacturers to make devices with the exact same specifications and a compatible pin-out in their own technology by going around the patents. These devices are perfectly legal and often support the same software drivers if PC interfacing is involved. A funny side fact is that many of these "clones", as you might call them, are in fact superior in performance compared to the original. It reached the point where claiming pin compatibility is a common marketing goal, this is good for all manufacturers involved because large companies will only use parts that they can source from multiple suppliers. So yes, by doing this FTDI broke the cease fire/gentlemen's agreement. This also means they'll probably be at the receiving end of several lawsuits involving their implementation of competitor's bus systems.