It doesn't matter whether your in two or four wheel drive when it comes to hydroplaning. Once your tires can no longer displace the water from under it and you have enough speed for the water to lift the wheel off of the ground, your going for a ride. Almost like on ice, four wheel drive may get you going but when it comes to traction to stop or maneuver, good luck with that too.
I usually see more 4WD in the ditch or smashed along the center divider when the weather is bad cause the driver's think their invincible. We get our fair share of crappy weather here in Michigan.
The rest of your post may be Ok, but its dead wrong about fluid dynamics, hydroplaning and 4WD, and thats from 50+ experience on wet roads with 4WD and decent tires. Because 4WD applies power to the front wheels, they will start to spin a bit as they start to lift, shed water, and dig in. So there is much less tendency for uncontrolled hydroplane. Now as far as stopping thats another issue as the tires in the water without traction are not spinning, just pushing water and acting as a hydrofoil. Think of what you would do in mudding. You want the tires spinning to shed mud, dig in to more solid earth, and perhaps grab enough traction. Water is thin mud
.
Anyway, I was just commenting of what advantage, albeit minor, that 4WD would have in wet weather. You can believe it or not, as its just fluid dynamics and physics that not everyone can get a handle on. Of course there is a point where you will hydroplane regardless, but spinning wheels shed water better, dig to the bottom of the puddle better and make for just a tad more control... but you don't want too much spin either. Spinning tires will also grab traction earlier than a stopped tire. So 4WD is better. The effect is more dramatic in slush ridges than water puddles.
Many of the folks you see in the ditch are those that have a tendency to panic and slam on the brakes when in trouble and then go for a spin. If you accidentally get into a bad situation (poor planing) using a bit of finesse or powering through may a better approach (but in traffic you also want to get away from the morons driving too fast and slamming on the brakes). Sometimes you are just screwed regardless.