Is this something we should consider for visitors?

That would be interesting

In effect, visitors who are coming to the UK from a country where you are required to apply for a visa for entry to the UK do have to have medical insurance because they have to prove that they can financially support themselves and not draw on public funds (including the NHS). The issue is that the NHS is very bad at claiming back the costs from visitors.

Cuba has required all visitors to produce details of their travel and health insurance on arrival at Immigration since at least 2014. If you don't have it you have to buy a policy via them there and then. However, I'm not sure how effective they are at collecting the money either. I've needed to use their health services on a few occasions and not once have I been asked for cash up front, to produce my insurance policy or give them card number etc before receiving treatment. On the contrary, I've always received very thorough and excellent care and been given an invoice only afterwards. As the cost on each occasion was either less than or only marginally more expensive than the excess on my policy I've usually just paid cash rather than get into the hassle of claiming a negligable amount but I have often wondered what would happen if it had been much greater. Would they have refused to treat me before sorting out the fnancial arrangements first? I'm not sure they would have done because their priority has always seemed to be treatment before money.

I see nothing wrong with compulsory insurance, but then if the statistics are to be believed over 50% of UK holidaymakers don't bother with insurance. The T&Cs of the tour operators require you to have insurance but they do not seem to enforce their own rules.
As for visitors to the UK seeking medical assistance and charging that is a thorny topic which I don't think we want to get into debating.

Are there statistics as to how many people book with tour operators these days, very few that I know, Airlines don't have any requirements re insurance and I'm always reading in the press about someone complaining that they can't get their money back from Ryanair etc. when they have had to cancel because of illness and haven't bought insurance. Who knows what will happen after Brexit as the EHIC may be no longer valid within Europe for UK residents.

What I find most worrying,is the number of people who tell me that they have travel insurance thru their Bank - they have no idea of the number of exclusions in these types of policy!!!

Ours is through Nationwide Dave but we have seperate cover for hubby's medical conditions.