Seaworthiness is defined by understanding the worst qualities of what you sail and adjusting thereof.
There is no one all answer...
Yeah - I know there's not a single answer. But, hey, what else do we have to do other than debate this until the second coming?
Anyway, I think your statement above really nails it. And most of the debates I've seen center around the "what do I need to go blue" question. But when you think about it, that question typically comes from newbies like me that don't have a clue what "blue" means.
CD's (and others) point that almost ALL sailing is coastal and island hopping puts that very starting point into question. It's really the wrong question to ask for the vast majority of sailors.
Maybe I'm trying to vein a line that's not there - but it does seem to have a distinction from the debates I've seen. The question should be what are the best production boats (fast, comfortable, strong) for cruising sailors that can stand up to stink when you get caught 2 days out?