again, net negative is being glossed over. whatever good and nice things there might be, if it is being used more for negative purposes, you need to consider is it worth it at all or was it rushed and needing more thought before the PoC was pushed to prod
How can you tell that the negatives were glossed over? Just by WebUSB's eventual launch? Have you considered that different people might have different value preferences than you?
It bas been and that's why Firefox refused to implement it. It's good that this is done with a plugin as it is not on by default as mist people do not understand the risks. Making it more difficult offers a bit more protection for most people.
Google is known for launching stuff in the webbrowser without thought from a security and privacy standpoint. They are business oriented, not privacy oriented.