If you need the things that XML has, no, JSON is not simpler. It is more complex. Every attempt to embed XML/HTML into JSON has resulted in something worse than XML/HTML... and they are all different, too, which is bad.

The main problem with XML is that most people don't need what it has. The main problem with XML in the late 1990s and early 2000s is that it was jammed in many places that did not need what it had, and put a bad taste in developer's mouth as a result. It's actually a good solution for its niche, and that niche is large enough it isn't going anywhere, but it is also still only a niche. In that niche you're crazy to try to jam JSON in; out of that niche you're crazy to use XML. The mythos that XML is useless persists because the latter category is a much larger one.