You sound rational. You may wish to incorporate the studies of Sleep Paralysis into your knowledge base. I experience "out of body" experiences, see demons and angels and aliens and many other strange things, even hear prophetic voices while awake, I can confirm events with people in the room with me, except that which occurs due to my waking dreams. Even the profound sense of infinite selflessness and love, or blushing with jealousy or terrible unfounded fear can be mental hallucinations in this state.
Agreed that the mind is capable of melding dream imagery with real world perceptions. Another simple example is how getting your leg caught or hearing knocking can manifest inside of dreams as your mind tries to make sense of it all.
The mind constructs elaborate delusions to make sense of the random synapse firings, but the structures of the brain yields commonalities (won by evolution) when stimulated -- That is what feelings are, ancestral knowledge encoded in you DNA about how to respond in certain situations that is generally favorable to preserving the genes. Thus common hallucinations are also observed, we have similar DNA, it's only logical.
Not sure how you reached many of these assertions or how this relates to the OP's point about subjectivity and science's lack of tools (or perhaps incompatibility) with regards to comprehending it.
To continue the OP's train, you can do some analysis of subjective experiences (though arguably just philosophical) by finding commonalities, discussing origins and evolutionary purpose, and searching for something objective that could be further studied. On this route, the most interesting question is why would this begin occurring as your brain shuts down? From an evolutionary psychology perspective, why would this be helpful to human beings?
I would argue two possibilities arise: to ease or to excite (with a possible third being your point of utter randomness). Personally, easing the dying mind seems to make sense but also feels like it would require intelligent design. To excite would be odd because an NDE usually involves dream imagery and thus would probably lower your chance of survival as your brain may be battling a centaur rather than the guy who just knifed you in the street. To be random is certainly plausible but I don't really understand why this would arise as your brain is beginning the shutdown process and (as noted in the original article) is even more active than waking state. The scientists even go as far as asserting that the brain is capable of "well-organized" thought. To me, the mere fact that your brain is creating a semi-sensible NDE puts a kibosh on the idea that this is random.