Yes, let's turn a blind eye to images of people being gunned down as they try to make it past the Berlin Wall, and of the South Vietnamese clinging to the last U.S. chopper out of Vietnam. Let's forget about Freedom of Religion, Freedom of Speech, and just about every other Constitutional right we have. Hey, Communism had free health care. Sure, the health care was crap, but it was free crap.
There are several factors at work here. First, we have an entire generation of new voters that were in diapers when the Berlin Wall came down, much less do they remember when Castro was a more prominent figure. Second, we have people who are well aware of what Communism did in Europe that will use the ignorance of the people that don't remember for their benefit. Third, some people are just idiots, and insist that the only reason something didn't work is because the right people haven't tried it yet.