Neither of those two accidents were as a result of the thrust levers not being "fully closed".
In the China Airlines case, the skipper cancelled reverse thrust at 100 knots, in spite of having touched down long and fast.
It was also later disclosed that as a deadheading crew member he had made the comment that "Going around must have been very shameful" for the captain of the flight on which he was paxing.
In the other instance you cite, it was then QF policy to use "minimum" reverse thrust.
When you think about it, this natty little design feature could be quite useful…
On the other hand it might be giving "advice" that is 180 degrees different to that which the crew is actually reviewing - ie. going around!
It might be more suited to aircraft that are being used for first solo!