I find the concept of an automatic descent due to (insert failure scenario) , especially given the possibility of nonsense input which could trigger same, not a little disconcerting.
Agreed. Over the ocean auto descent after pressurisation failure might be useful but in busy European & US skies a plummet without some sort of ATC clearance could lead to more serious consequences. A mid-air would clearly be more hazardous than temporary hypoxia for some passengers.