I don't really care about the plagiarism of MAGA. I didn't even know that was a Reagan thing until somebody pointed it out after Trump adopted that slogan. I'd always associated Reagan with Morning in America.
The only thing that bugs me about it now is that it isn't associated with any particular ideas or thoughts. It's just a euphemism for Trump now, and is used almost as a shorthand by a lot of Trumpers to avoid any real discussions.