I guess he had the benefit that his audience (mostly) had grown up with him. So it wasn't like he came out of nowhere, they felt like they knew him and could relate to him.
He wasn't this overblown ego like Kanye or this seemingly strange being like Lady Gaga. They had seen this cute, mind blowingly talented boy grow into this super incredible man that totally changed the page.
To a much, much lesser extent... Timberlake benefits by the same thing, because people have seen him grow from a singer in a boy band to a mature talented solo star. Before you all start, I'm not putting them on the same page talent wise!
Plus MJ always seemed quite humble and never bad mouthed other artists. It was only later stunts like the History statue and trailer that made him seem pompous (in my opinion) but whenever he was interviewed he seemed like an extremely humble and thankful guy.