The problem is that Elm's crowning achievement is that it took a lot of ideas from functional programming and produced an end product that is stunningly simple

The problem is that Elm's crowning achievement is that it took a lot of ideas from functional programming and produced an end product that is stunningly simple and easy to use -- even simpler and easier than most non-functional languages. Speaking as an avid Haskeller who revels in the arcane and abstract, PureScript is just another inaccessible and alien functional language that most people will be immediately turned off by. It's not at all a replacement for what Elm achieved.