In addition to the other posted replies, it's bad software engineering. You really can't be confident enough in your logic to ever start issuing DESTROY_HARDWARE() commands of any kind, short of the small set of very specialized programs that may be deliberately used for such things (FPGA programmers, etc). Any error whatsoever and you may end up nuking your real customer's hardware. Bad plan. Same reason why programs that think they are pirated shouldn't run around being actively destructive... some real customer will find some way to tickle that code, if only through bad hardware, and now you're in trouble.
To a first approximation, all code eventually runs. Relatedly, never put an error message into your product you wouldn't want customers to see, because they will.
I can't find it anywhere, but I remember reading about a software company that wrote an office suite for early computers (like DOS or possibly even pre-DOS), that would detect if it was a legal copy, and if it wasn't a legal copy, would delete your data. I seem to recall that they got slammed by the legal system pretty hard, which is one possible reason for why software companies don't do it nowadays. I personally see this as an action on par with, or worse then, the software company I mentioned's actions.
Making alterations to someone else's property without their consent for the express purpose of rendering it non-functional is commonly called vandalism.
In a culture with intellectual property laws I'm not sure that's true. Is it legal to destroy counterfeit handbags commonly sold on the street? Honest question, the police seem to do it frequently.
The label printed on the outside of the plastic package of the chip is the only thing that's illegal, since it's depicting FTDI's trademark. Scrape that off and you've got a 100% legal compatible clone. Whoever decided to use the clones in any given device may be be in breach of a contract if the use of genuine FTDI chips was specified, but that may easily not be the case. (The clones also violate USB specs by using someone else's VID, but that only prevents them from labeling the product with the trademarked USB logo.)
Also, possession of the fake chip as an end user is no more illegal than owning fake Louis Vuitton stuff. It's the sale under false pretenses that gets you in trouble.
"Illegal" is an extremely broad and imprecise way to describe a physical object.
Imagine I buy a car from a dealership, and without my knowledge the dealer has swapped out the original radio for a cheap counterfeit. I guess technically you could argue that makes the car "illegal" but it would be absurd to suggest that the manufacturer has the right to come to my house and slash my tires.
As I see it, it's not about whether "fake chip users" are obeying the laws; the burden should be on FTDI to justify its willful property damage.
To the extent that there is a violation of law involved in the manufacture, sale, or use of the chips (and such violations are much more likely in the first two cateories), there are legal remedies available for those violations, which generally require proving that a violation occurred and that the person against whom remedy is sought is the appropriate person against whom to seek a remedy.
To the extent the violations are with manufacture and sale, the user is not generally the appropriate target, even if destruction of the device was an appropriate remedy.
I could sort of understand it if the driver refused to work and popped up some dialog that said "You're using a counterfeit FTDI device, here's how to get an official device. Sorry this driver is not compatible with unofficial devices." However if it just silently bricks the chip then consumers will have no idea what's wrong. They'll think their Arduino clone is broken or they can't talk to their Raspberry Pi for some reason. I doubt they'll make the connection that the FTDI chip in their device is a clone and understand what to do to fix it.
Dumb question maybe, but why?