Yes renouncing before a Brazilian Judge and renouncing in front on a consular officer at an embassy after you have have paid a big fee are two very different things. It is basically a matter of swearing your allegiance.
I can understand requiring some kind of reporting when income is originating from within the country. That should be taxable. But if you live and work and bank in another country, you never enter the US and never collect any money from the US you still must report your income and accounts overseas. The law was created to go after rich people who live in the US but were hiding assets outside the country to avoid taxes. It has had a big impact on the 6 million+ Americans who live abroad though and aside from a passport have nothing to do with the country. I would argue that such information is none of the IRS's business and violates peoples privacy. 95% of the time once these forms are filed it is the case that no taxes are owed. So, by threat of fines and criminal penalties people are forced to spend time, money and effort every year to file a return proving that they don't owe anything.
Maybe, just maybe, most people who reach retirement age after paying off their 30+ year mortgages, and saving their entire lives can scrape together a $2mil net worth. That seems unrealistic though. The average retiree's 401k in America when they reach retirement age is worth about $25k. Poverty of the elderly is a huge problem. Its off subject though. Someone that age who moves to Brazil to retire would probably have little use or interest in naturalizing if they have a permanent visa. The benefits are more likely to be seen by younger folks who are still in the workforce and travel frequently.
About the property taxes in Floripa. No I had not heard about that. It is not terribly surprising though. Still, even when doubled I bet the rate would be lower than what Americans are used to paying when the city, county, and school taxes are all added in.