With all due respect, posts like yours are a disservice. I'd like to explain why.
First, you make the blanket statement that because you have been cruising for MANY years without passports, they're unnecessary. But you don't say that you've never cruised to the MANY places in the world where passports are absolutely required. We just returned from a Baltic cruise. Do you reckon we needed our passports? Of course we did. At the very least you should have said that your non-US cruising has been limited to the Caribbean, Mexico, Canada, and maybe Berumuda. However, Canada is now looking unfavorably on inferior documentation, and may soon absolutely require passports.
Which brings me to the second point. You know how stockbrokers have to say that "past performance is no indication of future results?" Well, it's that way with immigration laws, too. What you could slide by with yesterday may be unacceptable tomorrow. But you can count on the fact that the passport will always be the trump card. So the "high price" (which boils down to about five bucks a year or so) represents peace of mind--and a faster trip through some immigration points--for those of us who do believe that "passports are the way to go."
I don't mean to be disrespectful of your point of view, but your post could actually mislead people into thinking that passports are never required on cruises, which is obviously not true. Remember that many who read these boards are novices who don't read between the lines.