In fact the only reason for the swim test is tradition.
As you can see reading this thread, there are many who think of swimming as being somehow a reasonable reaction to a diving emergency. It's not. It's foolhardy and dangerous. The swim test was removed because putting swimming in the middle of a dive course sent the wrong message about the appropriateness of swimming as a reaction to any diving situation. For that reason, and the reason of it not having anything to do with teaching diving in any sense, it was removed as a requirement.
The ocean is no place to swim, but it is a great place to dive.
Even your story proves the point. It was not swimming that saved lives, it was PFDs. Gear not skill.
Every year, 'swimmers' get pulled from the ocean in Hawaii by lifeguards. Inevitably, the comment is that the rescued person thought that since he could swim he would be ok. The lifeguards know better than to go in the ocean without gear, even though they are fantastic swimmers. And that's in situations where the person is in easy reach of the shore. Put them in a situation where dive boats go, and there is no way swimming would help them do anything but get themselves in trouble.
I'm not sure where the test was actually removed from the courses. It was included in my PADI OW course and the instructor gave the class the option to just swim or do MFS.
I've pulled a few people out of the ocean myself, and some of them did get in trouble because they thought they were better swimmers than they were. A standard test might have helped them see different.
I agree with you about the gear. If I had on my gear, no way I would drop it and try to swim out of trouble. That would be crazy. It’s finding myself in the water without gear that would be the problem. Is it likely? Probably not. Is it possible? Sure. Is it more likely for people who go out into deep water on boats all the time for fun? Why yes, I believe it is.
I keep thinking about the example of the two girls that Jill from Phoenix offered. They didn't want to remove their gear to climb back into the six-pack because they couldn't swim. The image I have in mind is that little boat flying across the water between dives with them sitting there in full gear because they can't swim...or maybe they dropped the BCDs and put on a life vest?
I maintain my original point, if you're doing anything that has you around deep water regularly, learn to swim.