> It seems completely mad that an automated flying mode could be engaged in such an obviously suicidal way on a modern bulk carrier aircraft, without so much as a blaring warning and red flashing lights.
You are assuming that there weren't blaring warnings and red flashing lights. Probably there were many.
> To elaborate, why isn't an autopilot "aware" of whether the aircraft is taking-off/landing or in-flight?
Autopilots are much simpler systems. I don't know how much you know about them, but people in the general public believe they are some AI which flies the airplane from A to B. In reality they have much more common with a thermostat than an AI. You set a target heading and the plane will bank to match it. You set a target height and the plane will pitch to match it. Yes yes, they have many modes, and some modes can do much more complicated things than these, but it is not there to replace the pilot. It is a tool to alleviate dead simple piloting tasks so the pilots fatigue less on long flights.
Just as an example how simple stupid they are: You can command the autopilot to climb, and if you don't adjust the throttle appropriately (either manually, or by enabling the autopilot to adjust it) then the plane will use up all the airspeed during the climb and the autopilot will happily fly it into a stall.
Also just a general rule about aviation incidents/accidents: It is a good idea to wait for a proper investigation report before running far with all kind of assumptions about what happened, and therefore what you think should be changed.