I can't speak for everyone but for me the type system is not what made Haskell difficult. I loved it. What made it difficult was laziness. I'd find myself always trying to reason about execution (even though most of the time you probably shouldn't). Laziness might even be fine in a world built around it, but for a language to be practical it has to interface with systems that are not designed that way (numerous external libraries developed in strict languages). This isn't to say laziness is bad, or even worse - just that for a typical engineer switching from strict languages it's a large mental tax.
The problem is while you can adapt and bolt on some functional programming techniques to existing languages like C# - to bring the power of the type system to an existing language is all but impossible. There are a few areas it has started to sneak in, like nullable types. But from my naive perspective you just can't bolt on an expessive type system like that, let alone a dependently typed one.
The problem is while you can adapt and bolt on some functional programming techniques to existing languages like C# - to bring the power of the type system to an existing language is all but impossible. There are a few areas it has started to sneak in, like nullable types. But from my naive perspective you just can't bolt on an expessive type system like that, let alone a dependently typed one.