First, I have to say you haven't really made it clear to me what the distinction is between perspective and point of view. The three main perspectives you've described here match pretty well with the usual general descriptions of POV - you even used the term 'point of view' in your second-last paragraph. You hinted that you think there's a difference in an editorial comment, but unless you meant that 'perspective' was a broad grouping of related POVs, I don't see the distinction.

I do have a few other quibbles with how you describe some of the different perspectives.

In your description of the first person, you call it "a dominant form of writing" and say, as many do, that it is a more personal perspective and one that leads to a greater connection with the reader. This has not been my experience. What I've seen is that it is used mostly by beginning authors who think that it gives them a connection with the reader that is simply not supported by the level of characterization in their story. In quite a few cases, it gives them such a false sense of connection with the reader that they put less effort into actually making that connection than they otherwise would have. It can be very powerful when well used, but is a lot harder to do well than it looks. It is not intrinsically more "personal".

In your description of third person, you mention that it "lacks intimacy [...] and the story quickly becomes bigger than the plot itself" which again, has not been my experience. Third person can be extremely intimate - it depends on the distance chosen, as well as the writer's style and skill. Third person omniscient is certainly a very distant type, and can lack intimacy, but there are many much closer types of third.

There is a very good reason that third person is the most prevalent of all the point of view classes, and none of them are due to what you describe as the characteristics of third person. Only in third person omniscient (very rarely used these days) is the narrator "an all-knowing, all-seeing entity"; "no action is questioned" applies (or doesn't) in equal measure to all three of the types of POV; and I'm not quite sure where you got the impression that "the decisions made by each character are without reproach" - in first person, the decisions made by the narrator are just as much "without reproach" as those made by the POV character in third. That is, unless you are in omniscient or limited-omni (again, very rare these days) in which the narrator is an observer not taking part in the story but expressing his opinions of the action.

As for how the different points of view should be used, well, I have a few disagreements there as well, mainly related to my quibbles above :-)

You write: "in the case of the epidemic, if you followed only one character, you would have trouble convincing the casual reader of the global impact of the virus."

I would like to offer a counter-example: if you show a planet blowing up, people don't feel for the global disaster, they think "wow, that was a big boom" - it doesn't draw them into the story. If you put them in a sinking car with the main character trying to get the doors open against water pressure and a shrinking airspace, they're there... unless you completely blow it and make that very tense situation boring.

In your global epidemic, you can show the huge impact through only one character's experiences - and it would probably have more of an impact on the reader. It's hard to care about a crowd except in an abstract way. We are basically "hard-wired" to care about individuals, not crowds; communities, not nations.

In your helpful stranger example:

"For example, if we are writing from first-person perspective, then we don't automatically know the motives driving the stranger that comes to our protagonist's aid. Instead, we have to plot around that, either by simply having the stranger state his motives, which is not very interesting, or having our narrator catch glimpses of the stranger's actions that reveal his characteristics. Knowing in advance that this stranger does not have a voice exposes the need for justification through his actions."

you neglect to mention that regardless of the POV chosen, you will have to explain the stranger's motives through his actions if you want your story to stay interesting. As you mentioned, having the stranger simply state his motives is not interesting. In a POV that allows us access to the stranger's thoughts, having the narrator state his motives is similarly uninteresting. In both cases, his motives should be shown through his actions to the extent that they're important to the plot. (This is the "show, don't tell" guideline that is good advice in general, but with which I take issue when it's used as an absolute rule.)

And finally, your mix & match example is rather uneven. While, as you say, dialogue uses first person pronouns even in a story told in third person, a passage must have a clear point of view character or there is a real risk of confusing the reader. In tight third or first, the second person sentences of your example could well be the POV character musing to herself, but the combination of third and first person left a bit too much ambiguity - deadly to the pace in a scene of mortal peril. Who is Dirk pointing the harpoon at? Is it the "I" character as hinted at in the final sentences ("I had no idea what impalement would feel like, and I wasn't ready to find out.") or not? If so, his target should be called "I", not "the target". If not, the comment about finding out what impalement felt like is completely out of place.
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Who needs to be big and burly when you can just apply physics?