"Wouldn't like to be onboard when the mechanism failed to operate on arrival at the gate"
No... but then there are various mechanisms in the average aircraft where operational failure would also inspire a deep wish not to be onboard at the time!
In this case, it would be easy to have a manual override that could be operated by cabin crew. I think the expense and complexity, plus the lack of any suggestion that it would do any good other than to lower the blood pressure of the crew, means it's not going to become an FAA requirement any time soon...
R