Again, I tend to agree with you. We have a 2000 First 47.7, and it has been through some pretty rough stuff and she takes it with ease. We were even in the Mac Storm.
However, all of those things suggestions that you made apply to any boat.
Can you inspect the chainplates on your Hunter? I remember this 80s Hunter 34 that had steel chainplates bonded in the hull that you couldn't even inspect. Chainplates rust, rig goes down. Ouch. Anyone with a Hunter 34 better get to inspecting their chainplates.
I think you're right about the boat being fine if it was simply closed up and just bobbed around in the Atlantic. There are plenty of stories of just that - boats being found floating months or even years after a rescue (or worse, MOB).
What I mean by "sailed prudently" is basically this:
1. Make sure your boat is dry and secure, then test it with off-shore shakedowns, prior to heading out . I've seen several stories now where wet below-decks, or stuff flying around have caused the crew to crater or fully pack it in and call for rescue. The floorboards you mention is a great example. The Yachting Monthly Crash Boat Youtube series is fantastic for getting a sense of what needs to be considered. Simply addressing leaking hatches, or chainplates, or cockpit drainage, or seacock hose clamps, proper safety equipment, proper tools, etc. and like is a very straightforward way to ensure a safe, dry passage. It's not that hard.
2. Carefully choose your weather windows. Sure, there are stretches which will go far beyond a reliable immediate forecast. But weather information is so good these days that if you pay attention to it, you can avoid most all the nasty stuff (see Hal Roth).
3. Be conservative in your decision-making. Actually one of the best examples of this was the Bumfuzzles. Their RTW blog is replete with examples of them deciding to stay put in an area for weeks on end until the conditions were mellow. This worked very well for their level of (in)experience at the time. But it's the epitome of not sailing to a schedule. You go when things are comfortable.
4. Sail the boat you have. Again, the Bumfuzzles are a good example of this. On their cat, they typically had very little sail flying. They probably over-relied on their engines because of this during their run (I'd rather sail), but they never got into serious trouble either. So it's hard to argue that approach. The point here is that your boat will be able to do certain things very well - and other things not so well. For example, if your boat pounds and you get caught in a blow with your destination upwind - why not drop a JSD and hangout for a day or two instead of relentlessly beating into it and breaking stuff? There's rarely a need to push the boat that hard (see Hal Roth).
Beyond that, everyone has their own idea of what's necessary to go off-shore. And with all due respect to Jimmy C - there are lots and lots of boats out there that successfully traverse the world's oceans with wildly unprotected, yet very strong and capable rudders.
So that's basically what I mean.