You never can be too prepared.
I think it all comes down to that.
I have read and note the experiences others here have had offshore. In comparison probably some squalls, a few good blows and some heavy swell is the worst I have ever encountered on an offshore passage.
Whether this makes me lucky I am not sure? I guess you are always unsure how you will handle that 'perfect storm' until you are in the situation. Part of me would like to face the worst and know that I would be up to task.
So maybe this is only my limited experience and good luck talking, but I believe there is an inherent risk in sensationalising the offshore heavy weather risk to the detriment of approaching offshore sailing and indeed all sailing with a holistic view to safety.
Statistics tell me there is more chance of my boat catching on fire, or of my family being blown up by the gas oven, or drowning in strong current in a anchorage , or being hit by the boom (as you mentioned above), or going overboard in benign conditions than the perfect storm ever ending me.
I also note the amount of vessel loses and threat to life when run aground on lee shores or when dragging anchor and wonder perhaps if it is tradition from earlier sailing days that makes us all so obsessed by the 'here there be dragons' approach to those conditions we perceive are waiting to attack us the moment we are 100nm offshore.
Perhaps it is more a peculiar condition specific to US east coast sailors?
The Chesapeake, ICW and those island things down the bottom are all fairly benign and the moment you folk sail 'offshore' things do begin to get quite nasty in that part of the world.
Here in in the Tasman Sea in the wrong conditions with our rugged coast where protection lies only behind barred river entrances if you are out in a blow where the whole coast becomes a lee shore you don't run for port. You sail like hell to get sea room. So this whole bluewater/coastal discussion seems kind of cute to us. Who not just sail good boats and sail them well all the time?
I will agree that when conditions deteriorate experience helps. But you only get experience one way.
How big is big enough? Well to me thats just the wrong question to ask.