Medicare is socialized, gov't healthcare, and Americans love it.
Calling out socialized, gov't healthcare as unambiguously bad seems to ignore this fact.
Expanding one of the most loved gov't programs to cover more people seems like good governance. At least, I can see why it sounds like a good suggestion, prima facie.

Huge expenses in healthcare come from the inaccessibility of preventative medicine and of early treatments to financially challenged people.
It's not uncommon for a person to get sick, but to think that it's not that bad, and they don't need to see a doctor unless they're really sick. They can't afford a $100+ doctor's bill unless it's truly a life-threatening illness. They just don't find out it's life-threatening until the cost of treatment has skyrocketted from catching it in the early stages. They couldn't afford a $100 bill and now they're inpatient at a hospital that costs over $1000 per day.

The cost of treatment at that late stage is astronomical compared to if it could have been caught early on. People whom can't afford those early visits are costing all of us $1000's more in tax dollars for treatment costs than if we'd just put up the initial capitol to make preventative check-ups a human right. Yes, it'll cost us a lot of tax dollars to make these services available to all, but it's already costing us much more in tax dollars to deal with.