And these days you can use a Dropbox API app to get something just as good and in some ways better than the public folder. Check out https://www.site44.com/ It has no problem linking to free Dropbox accounts. (though it is a paid service...)
But yea, it certainly sucks to have to remove functionality, especially from such long time and loyal users. I just want to make the argument that this wasn't done to somehow trick people into upgrading their plans, but with the goal of creating a better product (which sometimes means a simpler product).
edit: For a timeline breakdown...accounts created after late 2012 stopped getting public folders. Public folders for legacy users kept working until March of this year. That's ~4.5 years of support for a feature only accessible to legacy accounts. They certainly did not foresee Dropbox Professional when they made the decision to stop creating more public folders. https://www.dropbox.com/help/files-folders/public-folder