Well, if a Brit likes it, I have no problem with that - it’s his system and he knows it. Generally, the problem with these health care systems is when someone gets old and ill. All of my facebook friends are generally on the youngish side. The one friend I have who is 75, does not like it much and gets treated here in the USA because he’s married to an American and has good Screen Actors Guild coverage. I don’t know how he’ll feel once Obamacare takes over.
My parents are 75 and 70, and find the NHS as good as it always was. In my life, I have not encountered any serious problem with my health care (thankfully minor) or my parents. As you said, we know it, faults and all, most Americans go on what horror stories they read or are told by talk radio/Fox. Almost all have never tried it, most have never even been to the UK or abroad. And yes, the same in reverse for the US system (much maligned in the UK).