To take you analogy a little farther The Honda Accord is low maintenance, but when maintenance is required, you better have an obd-ii reader, new injectors when the old ones die, etc.
The VW bug requires constant maintenance, but a 12 year old can do it. (At least, thats how old I was when I started, I trust there are younger somewhere) The engine is accessible and simple. The parts are readily available, and everything that can possibly go wrong has been well documented in books, on the Internet, etc.
In many myths the ocean is known as the great womb and tomb, from which life comes and to which it shall return. It beats mountains into sand. If you want a low(er) maintenance boat, get a trailer sailor or find a place that will store it on the hard for you. Both are going to be interesting dilemmas in the size range you mentioned. Anything left in the ocean will be constantly under attack. Personally, I'm a fan of something I can easily work on.
Beyond that, many of the questions are ones of how things break.
Fiberglass tends to wear better than most things, including steel, when looked at weight-for-weight. Rigging? Stainless is less likely to corrode, but it doesn't fail in as predictable a manner, nor with as much warning as traditional rigging.
When you mention watermakers, we can broaden the scope easily. EVERY system you have will have it's own maintenance schedule, required set of spares, documentation to memorize, store somewhere safe, and then store a copy of on the boat. Your head, refrigeration, engine, generator, solar, wind, any power winches (any non-power winches) stearing, any nav gear, all the electrical, radios, phones, etc. If you want 0 maintenance, then find systems you can live without, and take them off the boat. That might sound horribly cynical, but when you start really simplifying like that, it's kinda cool how much fun sailing is when you remove everything unnecessary. Beyond that, it's a question of finding what works for you, and finding out what each system really needs to be bulletproof. How often do you want to rebuild your marine head? it's not fun, but doing it on a schedule works so much nicer than realizing a gasket failed and it won't pump right after someone used it, and rebuilding in those conditions.
As far as cored decks, if you want "performance" anything, then cored decks/hulls are going to be lighter and stiffer than solid decks of anywhere near the same thickness. The only time coring is an issue is if someone put something through the deck/hull without doing it right (drill, fill, drill) This can be checked for and remedied fairly simply if the deck's not already screwed. Further, modern boats are often cored with high tech materials which, unlike plywood which was the classic coring material, are much more resistant to water damage. They're still no substitute for overdrilling, filling with epoxy, and then redrilling, but they can keep things solid for longer if the previous owner did something stupid.
Regarding any system. Saildrive vs shaft, gas vs diesel, atomic 4s are horrible, atomic 4's are awesome, etc etc etc, it seems to me, and this is just my observation, as I've only owned one boat, and crew on a few, I'm not an expert, but from watching everyone talk about it, and from my limited personal experience, it seems that it's really just a question of knowing your equipment, and keeping up to date on maintenance. If you do that, everything else should take care of itself.
There will still be emergencies, that's what the oceans there for, but a well maintained boat is a thing of beauty, and if you take care of her, she'll probably take care of you through just about anything you're willing to take her through.
Hope that helps.